Optical disc and physical address format

ABSTRACT

An optical disc medium comprises a track groove, along which main information is recorded. The track groove is divided into a plurality of blocks. The plurality of blocks each include a plurality of frames. The plurality of frames each include one shape of wobbles indicating sub information, among a plurality of prescribed shapes of wobbles. The plurality of blocks each have address information. The address information is represented by a string of at least one piece of sub information represented by the shape of wobbles of at least one of the plurality of frames.

This application is a continuation of U.S. patent application Ser. No.11/839,001 filed Aug. 15, 2007 now U.S. Pat. No. 7,596,076, which is acontinuation of U.S. application Ser. No. 11/380,262 filed Apr. 26,2006, now U.S. Pat. No. 7,327,660, which is a continuation of U.S.patent application Ser. No. 11/361,801 filed Feb. 24, 2006, now U.S.Pat. No. 7,257,073, which is a continuation of U.S. patent applicationSer. No. 10/111,823, filed Apr. 26, 2002, now U.S. Pat. No. 7,116,624,which is a 371 of PCT/JP01/07499, filed Aug. 29, 2001.

TECHNICAL FIELD

The present invention relates to an optical disc medium for recordinginformation (for example, digital video information) at a high density,and an optical disc apparatus and an optical disc reproduction methodused for the optical disc medium.

BACKGROUND ART

Recently, the recording density of the optical disc media has becomeincreasingly higher. In general, a recordable optical disc medium hastrack grooves therein in advance, and information is recorded along thetrack grooves, i.e., on the track grooves or an area interposed betweenthe track grooves (referred to as a “land”). The track grooves aresine-like wobbles, and the information is recorded in synchronizationwith clocks generated based on the period of the wobbles. Addresses areprovided along the track groove in order to record information atprescribed positions on a recording face of the optical disc medium.Three exemplary structures for providing addresses will be describedbelow.

(1) Japanese Laid-Open Publication No. 6-309672 discloses an opticaldisc in which wobbled track grooves are formed locally andintermittently and address information can be reproduced as so-calledpre-pits. In this case, an address-only area and a data-only area forrecording information exist on the track groove.

(2) Japanese Laid-Open Publication No. 5-189934 discloses an opticaldisc in which frequency-modulated wobbles are provided and addressinformation (sub information) is recorded using the frequency of thewobbles. In this case, data information is overwritten on the addressinformation.

(3) Japanese Laid-Open Publication No. 9-326138 discloses an opticaldisc in which pre-pits are formed between adjacent track grooves andaddresses are formed by the pre-pits.

In consideration of the higher density recording which will be requiredin the future, all the above-mentioned structures have their ownproblems.

In the structure of (1), the space for data is reduced by the spacerequired for the addresses (so-called “overhead”). Thus, the memorycapacity is inevitably reduced by the space for the addresses.

The structure of (2) has the following problem. The wobbles areoriginally provided mainly for the purpose of generating clocks forrecording information, and thus are preferably formed with a singlefrequency. When the wobbles are formed with a single frequency, highlyprecise recording clock signals can be generated merely by multiplyingand synchronizing a wobble reproduction signal using a PLL or the like.When the wobbles have a plurality of frequency components, however, thefrequency band to which the PLL can adapt itself needs to be reducedrelative to the case where the wobbles have a single frequency in orderto avoid pseudo lock of the PLL. Then, it may undesirably occur that thePLL cannot sufficiently follow disc motor jitters or jitters generatedby, for example, de-centering of the disc. This results in jittersremaining in a recording signal.

In the case where a recording film formed on a recording face of anoptical disc is a phase change film, the S/N ratio of the recording filmcan undesirably be reduced as rewriting is repeated. Even when thisoccurs, wobbles with a single frequency allow the noise component to beremoved using a bandpass filter for a narrow band. However, when thewobbles are frequency-modulated, the band to be passed needs to beenlarged in order to allow for the modulated frequencies. As a result,the noise component is mixed in with a wobble reproduction signal andthus further increases the jitters. Such an increase of jitters is notpreferable since the jitter margin is decreased as the recording densityis increased.

In the structure of (3), the pre-pits naturally influence reading of theinformation stored in the adjacent track grooves. Thus, it is difficultto provide a sufficient number of pre-pits each having a sufficientlength. Therefore, there is an undesirable possibility that the numberof detection errors is increased especially when the recording densityis significantly high.

In light of the above-described problems, the present invention has anobjective of providing an optical disc medium for minimizing overheadand describing addresses with wobbles having a single frequency, anoptical disc apparatus and an optical disc reproduction method forreproducing the optical disc medium.

DISCLOSURE OF THE INVENTION

According to one aspect of the invention, an optical disc mediumcompares a track groove, along which main information is recorded. Thetrack groove is divided into a plurality of blocks. The plurality ofblocks each include a plurality of frames. The plurality of frames eachinclude one shape of wobbles indicating sub information, among aplurality of prescribed shapes of wobbles. The plurality of blocks eachhave address information. The address information is represented by astring of at least one piece of sub information represented by the shapeof wobbles of at least one of the plurality of frames.

In one embodiment of the invention, the plurality of blocks each includea plurality of sectors. The plurality of sectors include the pluralityof frames. The address information is represented by a string of atleast one piece of sub information represented by the shape of wobblesof at least one of the plurality of frames included in at least one ofthe sectors.

In one embodiment of the invention, at least one of the plurality ofblocks includes a plurality of pieces of address information. Theplurality of pieces of address information are identical. The pluralityof pieces of address information are each represented by the string ofthe at least one piece of sub information.

In one embodiment of the invention, the plurality of pieces of addressinformation each include an order number, and the order number indicatesan order of the respective piece of address information among theplurality of pieces of address information.

In one embodiment of the invention, the address information isrepresented by a plurality of bits, and the plurality of bits arerepresented by the at least one string of sub information from a lowerbit to a higher bit.

In one embodiment of the invention, the plurality of blocks each includea plurality of sectors. The plurality of sectors include the pluralityof frames. The address information is represented by the at least onestring included in the plurality of sectors. Information indicating anorder of the sector among the plurality of sectors is represented by aportion of the at least one piece of sub information.

In one embodiment of the invention, information indicating at least oneof an error detection code and an error correction code is representedby a portion of the at least one piece of sub information.

In one embodiment of the invention, the track groove has anidentification mark provided therein indicating a leading end of each ofthe plurality of blocks.

In one embodiment of the invention, the identification mark is providedby cutting off the track groove.

In one embodiment of the invention, the identification mark is providedby locally varying a width of the tracking groove.

In one embodiment of the invention, the identification mark is providedby locally varying an amplitude of the shape of wobbles.

In one embodiment of the invention, the plurality of shapes of wobblesinclude a first shape of wobbles and a second shape of wobbles which aredifferent from each other in at least one of a rising gradient and afalling gradient, and the first shape of wobbles and the second shape ofwobbles indicate different pieces of sub information from each other.

In one embodiment of the invention, the plurality of shapes of wobblesinclude a first shape of wobbles and a second shape of wobbles which aredifferent from each other in a duty ratio, and the first shape ofwobbles and the second shape of wobbles indicate different pieces of subinformation from each other.

In one embodiment of the invention, the plurality of shapes of wobblesare provided on one edge of the track groove.

In one embodiment of the invention, the track groove includes anidentification mark indicating at least one of a leading end and atrailing end of the at least one string of sub information.

In one embodiment of the invention, at least one of the plurality ofblocks includes a plurality of the at least one string of subinformation. The identification mark indicates a leading end of the atleast one string of sub information. The identification mark has anidentical shape with another identification mark in the at least onestring of sub information in one block.

In one embodiment of the invention, at least one of the plurality ofblocks includes a plurality of the at least one string of subinformation. The identification mark indicates a leading end of the atleast one string of sub information. At least one identification markhas a different shape from the shape of another identification mark inthe at least one string of sub information in one block.

In one embodiment of the invention, the identification mark indicates atrailing end of the at least one string of sub information. Theidentification mark is formed by combining a first shape of wobbles anda second shape of wobbles which are different from each other in atleast one of a rising gradient and a falling gradient with a third shapeof wobbles which is a sine wave shape.

In one embodiment of the invention, at least one of the plurality ofblocks includes a plurality of the at least one string of subinformation. The identification mark indicates a trailing end of the atleast one string of sub information. The identification mark has anidentical shape with another identification mark in the at least onestring of sub information in one block.

In one embodiment of the invention, at least one of the plurality ofblocks includes a plurality of the at least one string of subinformation. The identification mark indicates a trailing end of the atleast one string of sub information. At least one identification markhas a different shape from the shape of another identification mark inthe at least one string of sub information in one block.

In one embodiment of the invention, the identification mark is providedby cutting off a portion of a land between adjacent portions of thetrack groove.

In one embodiment of the invention, the identification mark is providedby cutting off a land between adjacent portions of the track groove.

In one embodiment of the invention, single frequency dummy data isrecorded on the identification mark.

In one embodiment of the invention, the number of pieces of subinformation indicating a lower bit of the address information is largerthan the number of pieces of sub information indicating a higher bit ofthe address information.

According to another aspect of the invention, an optical disc mediumcompares a recording reproduction area and a disc management area. Therecording reproduction area includes a first track groove, along whichmain information is recorded. The disc management area includes a secondtrack groove provided in at least one of an inner area and an outer areaof the optical disc medium. The second track groove includes a pluralityof prescribed shapes of wobbles. The management information of theoptical disc medium is represented by a combination of the plurality ofprescribed shapes of wobbles.

In one embodiment of the invention, the plurality of prescribed shapesof wobbles include a first shape of wobbles and a second shape ofwobbles which are different from each other in at least a risinggradient and a falling gradient, and a third shape of wobbles which is asine wave shape.

In one embodiment of the invention, the first track groove includes theplurality of prescribed shapes of wobbles. The number of shapes ofwobbles indicating 1-bit information is different in the disc managementarea compared to in the recording and reproduction area.

In one embodiment of the invention, the first track groove includes theplurality of prescribed shapes of wobbles. The first track groove andthe second track groove are different from each other in the frequencyof the shape of wobbles.

In one embodiment of the invention, the first track groove includes theplurality of prescribed shapes of wobbles. The second track groove has alarger amplitude of the shapes of wobbles than that of the first trackgroove.

In one embodiment of the invention, adjacent portions of the secondtrack groove have a constant phase difference in the shape of wobbles ofπ/2×(2n+1), where n is an integer.

In one embodiment of the invention, the second track groove has a largertrack pitch than that of the first track groove.

In one embodiment of the invention, the identification mark is providedby varying a phase of at least one shape of wobbles in the track groove.

In one embodiment of the invention, the identification mark is providedby varying a frequency of at least one shape of wobbles in the trackgroove.

In one embodiment of the invention, the plurality of shapes of wobblesare provided at an identical period.

According to still another aspect of the invention, an optical discapparatus for reproducing an optical disc medium, which includes a trackgroove, along which main information is recorded is provided. The trackgroove is divided into a plurality of blocks. The plurality of blockseach include a plurality of frames. The plurality of frames each includeone shape of wobbles indicating sub information, among a plurality ofprescribed shapes of wobbles, the plurality of blocks each have addressinformation. The address information is represented by a string of atleast one piece of sub information represented by the shape of wobblesof at least one of the plurality of frames. The optical disc apparatusincludes a conversion section for reading the main information and thesub information from the optical disc medium and generating areproduction signal; a reproduction signal calculation section forgenerating a TE signal and an RF signal from a reproduction signal; areference clock signal generation section for generating a referenceclock signal from the TE signal; a level-sliced pulse signal generationsection for generating a level-sliced pulse signal from the TE signal; ablock mark signal detection section for detecting a block mark signalfrom the RF signal; and a sub information generation section forgenerating a sub information signal from the reference clock signal, thelevel-sliced pulse signal and the block mark signal.

According to still another aspect of the invention, a method forreproducing an optical disc medium, which includes a track groove, alongwhich main information is recorded is provided. The track groove isdivided into a plurality of blocks. The plurality of blocks each includea plurality of frames. The plurality of frames each include one shape ofwobbles indicating sub information, among a plurality of prescribedshapes of wobbles. The plurality of blocks each have addressinformation. The address information is represented by a string of atleast one piece of sub information represented by the shape of wobblesof at least one of the plurality of frames. The method includes thesteps of reading the main information and the sub information from theoptical disc medium and generating a reproduction signal; generating aTE signal and an RF signal from a reproduction signal; generating areference clock signal from the TE signal; generating a level-slicedpulse signal from the TE signal; detecting a block mark signal from theRF signal; and generating a sub information signal from the referenceclock signal, the level-sliced pulse signal and the block mark signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a track groove in an optical disc medium in Example 1according to the present invention;

FIG. 2 shows an optical disc medium in Example 1 according to thepresent invention;

FIG. 3 shows a track groove in an optical disc medium in Example 2according to the present invention;

FIG. 4 shows a track groove in an optical disc medium in Example 3according to the present invention;

FIG. 5 shows a track groove in an optical disc medium in Example 4according to the present invention;

FIG. 6 shows a track groove in an optical disc medium in Example 5according to the present invention;

FIG. 7 shows a track groove in an optical disc medium in Example 6according to the present invention;

FIG. 8 shows a track groove in an optical disc medium in Example 7according to the present invention;

FIG. 9 shows an optical disc medium in Example 7 according to thepresent invention;

FIG. 10 shows an address structure of the optical disc medium in Example7 according to the present invention;

FIG. 11 shows a track groove in an optical disc medium in Example 8according to the present invention;

FIG. 12 shows an address structure of the optical disc medium in Example8 according to the present invention;

FIG. 13 shows a track groove in an optical disc medium in Example 9according to the present invention;

FIG. 14 shows an address structure of the optical disc medium in Example9 according to the present invention;

FIG. 15 shows a track groove in an optical disc medium in Example 10according to the present invention;

FIG. 16 shows an address structure of the optical disc medium in Example7 according to the present invention;

FIG. 17 shows a track groove in an optical disc medium in Example 12according to the present invention;

FIG. 18 shows a track groove in an optical disc medium in Example 12according to the present invention;

FIG. 19 shows a track groove in an optical disc medium in Example 12according to the present invention;

FIG. 20 shows a track groove in an optical disc medium in Example 12according to the present invention;

FIG. 21 shows an address structure of the optical disc medium in Example13 according to the present invention;

FIG. 22 shows an address structure of the optical disc medium in Example11 according to the present invention;

FIG. 23A shows a structure of an optical disc apparatus in Example 14according to the present invention;

FIG. 23B is a flowchart illustrating a method for reproducinginformation on the optical disc medium in Example 14 according to thepresent invention;

FIG. 24 shows an optical disc medium in Example 15 according to thepresent invention;

FIG. 25A shows a track groove in an optical disc medium in Example 15according to the present invention;

FIG. 25B shows a track groove in an optical disc medium in Example 15according to the present invention;

FIG. 26A shows a track groove in an optical disc medium in Example 15according to the present invention;

FIG. 26B shows a track groove in an optical disc medium in Example 15according to the present invention;

FIG. 27A shows a track groove in an optical disc medium in Example 16according to the present invention;

FIG. 27B shows a track groove in an optical disc medium in Example 16according to the present invention;

FIG. 28A shows a track groove in an optical disc medium in Example 17according to the present invention;

FIG. 28B shows a track groove in an optical disc medium in Example 17according to the present invention;

FIG. 29A shows a track groove in an optical disc medium in Example 18according to the present invention;

FIG. 29B shows a track groove in an optical disc medium in Example 18according to the present invention;

FIG. 30 shows a conventional optical disc medium;

FIG. 31 shows a track groove in an optical disc medium in Example 20according to the present invention;

FIG. 32 shows a track groove in an optical disc medium in Example 21according to the present invention;

FIG. 33 shows a track groove in an optical disc medium in Example 22according to the present invention;

FIG. 34 shows an optical disc apparatus in Example 14 according to thepresent invention;

FIG. 35 shows a track groove in an optical disc medium in Example 19according to the present invention; and

FIG. 36 shows a track groove in an optical disc medium in Example 15according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by way ofillustrative examples with reference to the attached drawings.

EXAMPLE 1

FIG. 2 shows an optical disc medium 20 according to Example 1 of thepresent invention. The optical disc medium 20 has a recording face 101,which has a spiral track groove 102 formed therein. As shown in FIG. 1,the track groove 102 has shapes which are different on a block-by-blockbasis. In FIG. 1, a block mark (identification mark) 210 is a cut-offportion in the track groove 102 and shows an index indicating a leadingend of each block.

Each block is divided into N number of sectors 25 (N=32 or 16), and eachsector 25 (sub block) is divided into M number of frames #0 through #25(M=26). Each frame (fundamental unit) has a prescribed number of wobbles26 or 27 in a periodical manner. The wobbles 26 and 27 have differentprescribed shapes from each other, and represent sub information (“0”,“1” or “S”). One type of sub information (“0”, “1” or “S”) isrepresented by one shape of wobbles 26 or 27. The type of subinformation and the shape of wobbles (wobbles 26 or 27) are in aone-to-one relationship. More specifically, the wobbles 26 and 27 bothhave a generally sawtooth shape, and have different rising shapes (orrising gradient) and falling shapes (falling gradients). The wobbles 26or 27 are formed in accordance with the type of sub information (“0” or“1”). A string of sub information is represented by a combination of thewobbles 26 and 27.

The difference in the rising gradient and the falling gradient betweenthe wobbles 26 and 27 can be easily detected by a differential push-pulldetection signal as follows. A scanning laser beam is directed to thetrack groove 102, and a differential signal indicating the differencebetween the light amounts received by detection areas of a lightreceiving element divided along a direction perpendicular to the trackgroove 102 (a radial direction) of the optical disc medium 20 (i.e., apush-pull signal) is generated. Thus, a detection signal having a risinggradient and a falling gradient which vary in accordance with whetherthe sub information is “0” or “1” is obtained. This difference in therising gradient and the falling gradient can be easily identified by,for example, differentiating the detection signal.

Thus, the type of the sub information can be detected by the size of thevalue obtained as a result of differentiation. When differentiation isused, however, a noise component is naturally increased. In an opticaldisc medium having an inferior S/N ratio, a detection error isreasonably expected. In this example, each pattern of the wobbles 26 and27 is repeated a plurality of times in order to enhance the reliabilityof detection.

Main information (for example, rewritable user data) is recorded in ablock unit 241 along the track groove 102 from the block mark 210. Theblock unit 241 has a prescribed length, for example, 64 kB (or 32 kB).The main information can be recorded as recording marks 28. Therecording mark 28 is recorded by performing a phase change of arecording layer. A block unit is a unit for information processing, andis, for example, an ECC block. The block unit 241 is divided into 32sectors 25 when N=32 (or 16 sectors 25 when N=16). Each sector 25 is asub block having a length of 2 kB. Each sector 25 is divided into 26frames #0 through #25 when M=26.

A frame is a fundamental unit of information recorded on the trackgroove 102. In FIG. 1, frame #0 is represented by reference numeral 22and frame #1 is represented by reference numeral 23. As exemplified bythe frames 22 and 23, each frame includes one type of wobbles formed ina periodical manner in advance. In this way, 1-bit sub information “0”,“1” or “S” is described in each of the frames 22 and 23. A 26-bit (M=26)sub information group included in each sector 25 indicates a block ID(address information) of the corresponding block unit 241. At a leadingend of each of frames #0 through #25, a SYNC mark is recorded. A SYNCmark is a synchronization signal recorded to represent a leading end ofeach frame of the main information when recording the main informationas a recording mark 28. A period of wobbles acts as a reference clockfor synchronizing the rotation of the optical disc medium 20 andrecording signals and is also used as a synchronization signal whenreproducing the address information.

The block ID can include an error correction code, an error detectioncode, or a parity code or the like for correcting or detecting detectionsignals, in addition to the information indicating the address.

The frame 22 includes only the wobbles 26 having a gentle risinggradient and a steep falling gradient. The frame 23 includes only thewobbles 27 having a steep rising gradient and a gentle falling gradient.When, for example, one frame includes 8 wobbles, one sector 25 includes8×26=208 wobbles (including the wobbles 26 and 27).

The sub information group recorded in the sector 25 can be correctlyidentified so long as the difference in the rising gradient and thefalling gradient between the 208 wobbles 26 and 27 can be detected as awhole despite some detection errors caused by the noise. The readingreliability is further enhanced by repeating the same block ID 32 times(when N=32) or 16 times (when N=16). According to an exemplary specifictechnique for identifying the sub information group, a differentialwaveform of the push-pull signal is sampled and held at each rise andeach fall, and a logical product of the rising gradients and a logicalproduct of the falling gradients are compared to each other. In thisway, the noise component is cancelled and only the sub informationcomponent can be extracted.

In this example, the block mark 210 is a cut-off portion in the trackgroove 102, and thus it is not preferable to overwrite the maininformation in the block mark 210. The reason is because the reflectedlight amount significantly varies in accordance with whether there is agroove or not, and this significant difference acts as an externaldisturbance to a reproduction signal. In this example, an area includingthe block mark 210 is assigned as a VFO recording area 21. The VFOrecording area 21 is used for recording a VFO 211, which is a singlefrequency signal for adjusting the frequency of a PLL for reproductionof the main information which is recorded after the VFO recording area21. Even when there is a slight external fluctuation, the VFO 211 merelyacts as a local jitter and does not directly cause any error.Additionally, the VFO 211 has a single frequency and thus canfrequency-separate the external disturbance caused by the block mark210.

In this example, one block unit 241 (one block) is divided into 32 (or16) sectors 25, and each sector 25 is divided into 26 frames (frames #0through #25). In each of frames #0 through #25, wobbles 26 or 27 havinga shape corresponding to the sub information are formed in advance.Since the sub information group recorded in one sector 25 represents ablock ID, the same block ID (address information) can be formed inrepetition in the 32 (or 16) sector 25 included in the block unit 241.

In this case, the sub information group can include an order numberindicating the order of the repeated block ID (address information),i.e., whether each block ID is the fifth, tenth, etc. Such number isusable for finally determining the address number based on a majority.In addition, such a number provides useful information for signalprocessing, for example, which sector 25 in the block is now read orwhich sub information group in the block is incorrect.

In the case of an optical disc medium having a plurality of recordingfaces or layers, an order number of the recording layer can be includedin the sub information group. In this way, the recording face can beeasily identified.

As described above, in this example, one information block is dividedinto 32 (N=32) or 16 (N=16) sectors, and each sector is divided into 26(M=26) frames. In each of the 26 frames, wobbles of a shapecorresponding to the sub information are formed in advance. One block ID(address information) is formed in repetition in 32 (or 16) sectors inthe block. Thus, an address is formed without any overhead or withoutrequiring pre-pits to be required between the grooves.

The wobbles used in this example have a constant single frequencyalthough the wobbles have different rising gradients and fallinggradients in accordance with the type of sub information. Therefore, aclock signal for recording having reduced jitters can be extracted byfirst using a bandpass filter for allowing only the frequency of thewobbles to pass so as to remove a noise component and then synchronizingand multiplying the resultant frequency using a PLL.

The reading reliability of the block ID can be enhanced by repeating thesame block ID.

In this example, the block ID has 26 bits like the number of the frames.The number of bits of the address information is not limited to 26, butcan be any necessary number in accordance with, for example, the dataamount to be recorded on the optical disc medium or the type and systemof the error correction code.

In this example, the block unit is divided into 32 sectors with N=32 (or16 sectors with N=16). The present invention is not limited to such anumber of sectors.

In this example, the sub information is recorded in 26 frames includedin each sector with M=26. The present invention is not limited to such anumber of frames.

In this example, the sub information is recorded after being modulatedinto sawtooth-shaped wobbles. The present invention is not limited tosuch a shape of wobbles. The sub information can be recorded after beingmodulated into wobbles having a shape, for example, shown in FIG. 4 or 7as described below.

In this example, the block mark is a cut-off portion of the trackgroove. The present invention is not limited to such a form of blockmark. For example, the block mark can be modulated into wobbles having ashape, for example, shown in FIG. 5 or 6 as described below.

EXAMPLE 2

FIG. 3 shows a track groove 10 according to Example 2 of the presentinvention. The track groove 10 can be formed in the optical disc medium20 shown in FIG. 2 instead of the track groove 102 shown in FIG. 1. Inthis example, the track groove 10 has wobbles 28 indicating subinformation “S” recorded in a frame 24 in addition to the wobbles 26 inthe frame 22 indicating the sub information “0” and wobbles 27 in theframe 23 indicating the sub information “1”. As in Example 1, addressinformation is represented by a combination of sub information “0” andsub information “1”. The sub information “S” is provided at a leadingend of the block, and used for indicating the leading end of the blockinstead of the block mark 210 shown in FIG. 1. In this way, the overheadrequired for the block mark 210 can be eliminated. In this example, thewobbles 28 representing the sub information “S” have a steep risinggradient and a steep falling gradient.

EXAMPLE 3

FIG. 4 shows a track groove 11 according to Example 3 of the presentinvention. The track groove 11 can be formed in the optical disc medium20 shown in FIG. 2 instead of the track groove 102 shown in FIG. 1. Inthe first and second examples, one shape of wobbles is repeatedperiodically in correspondence with one type of sub information, andwobbles having different rising gradients and different fallinggradients are used for different types of sub information. In thisexample, wobbles 29 and 30 are formed so as to have different dutyratios in accordance with the type of sub information. Morespecifically, as shown in FIG. 4, the wobbles 29 indicating subinformation “0” recorded in a frame 32 is wider in one of a ridge or atrough (in the trough in the example of FIG. 4), and the wobbles 30indicating sub information “1” recorded in a frame 34 is wider in theother of the ridge or the trough (in the ridge in the example of FIG.4). Such a feature eliminates the necessity of differentiating thereproduction signal for identifying the type of sub information. Thereproduction signal can be identified simply by measuring the duty ratiousing a clock timer or the like. Thus, the influence of the noise can bealleviated.

EXAMPLE 4

FIG. 5 shows a track groove 200 according to Example 4 of the presentinvention. The track groove 200 can be formed in the optical disc medium20 shown in FIG. 2 instead of the track groove 102 shown in FIG. 1. InExample 1, a portion of the track groove 102 is cut off in order to formthe block mark 210. In this example, a block mark 212 formed by locallyincreasing the width of the track groove 200 is used instead of theblock mark 210. For recording or reproducing main information, a leadingend of the block can be identified by detecting the block mark 212. Useof the block mark 212 avoids the track groove 200 from being cut off,and thus the main information can also be recorded in the block mark212. As a result, overhead can be reduced.

EXAMPLE 5

FIG. 6 shows a track groove 201 according to Example of the presentinvention. The track groove 201 can be formed in the optical disc medium20 shown in FIG. 2 instead of the track groove 102 shown in FIG. 1. InExample 1, a portion of the track groove 102 is cut off in order to formthe block mark 210. In this example, a block mark 213 formed by locallyincreasing the amplitude of the wobble is used instead of the block mark210. For recording or reproducing main information, a leading end of theblock can be identified by detecting the block mark 213. As in Example4, use of the block mark 213 avoids the track groove 201 from being cutoff, and thus the main information can also be recorded in the blockmark 213.

EXAMPLE 6

FIG. 7 shows a track groove 202 and a land 203 according to Example 6 ofthe present invention. An optical disc medium in this example haswobbles 220 and 230 which are formed only along one edge of the trackgroove 202. Examples 1 through 5 concern a groove recording type opticaldisc medium, in which main information is recorded in the track groove.Another type of optical disc medium, which is of a so-called land-groovetype, is available. In this type of optical disc medium, maininformation is recorded both in the grooves and lands (areas interposedbetween two adjacent grooves) along the track groove 202. Example 1through 5 can be combined with the groove-land type of optical discmedium described in this example.

In FIG. 7, sub information “0” and sub information “1” are recordedalong one edge of the track groove 202. The wobbles 220 formed in aframe 221 indicate the sub information “0”, and the wobbles 230 formedin a frame 231 indicate the sub information “1”. In this way, the trackgroove 202 and the land 203 adjacent to the track groove 202 arerepresented by the same address. Main information is recorded both inthe track groove 202 and the land 203. By recording the main informationin this manner, the track pitch can be narrowed, and thus higher densityrecording is realized.

EXAMPLE 7

FIG. 9 shows an optical disc medium 800 according to Example 7 of thepresent invention. The optical disc medium 800 has a recording face 801,which has a spiral track groove 802 formed therein. As shown in FIG. 8,the track groove 802 has shapes which are different on a block-by-blockbasis. In FIG. 8, a block mark (identification mark) 810 is a cut-offportion in the track groove 802 and shows an index indicating a leadingend of each block.

Each block is divided into N number of sectors 825 (N=32 or 16), andeach sector 825 is divided into M number of frames #0 through #25(M=26). Each frame has a prescribed number of wobbles 826 or 827 in aperiodical manner. The wobbles 826 and 827 have different prescribedshapes from each other, and represent sub information (“0”, “1” or “S”).One type of sub information (“0”, “1” or “S”) is represented by oneshape of wobbles 826 or 827. The type of sub information and the shapeof wobbles (wobbles 826 or 827) are in a one-to-one relationship. Morespecifically, the wobbles 826 and 827 both have a generally sawtoothshape, and have different rising shapes (or rising gradient) and fallingshapes (falling gradients). The wobbles 826 or 827 are formed inaccordance with the type of sub information (“0” or “1”) A string of subinformation is represented by a combination of the wobbles 826 and 827.A string of sub information is represented by a combination of thewobbles 826 and 827.

The difference in the rising gradient and the falling gradient betweenthe wobbles 826 and 827 can be easily detected by a differentialpush-pull detection signal as follows. A scanning laser beam is directedto the track groove 802, and a differential signal indicating thedifference between the light amounts received by detection areas of alight receiving element divided along a direction perpendicular to thetrack groove 802 (a radial direction) of the optical disc medium 800(i.e., a push-pull signal) is generated. Thus, a detection signal havinga rising gradient and a falling gradient which vary in accordance withwhether the sub information is “0” or “1” is obtained. This differencein the rising gradient and the falling gradient can be easily identifiedby, for example, differentiating the detection signal.

Thus, the type of the sub information can be detected by the size of thevalue obtained as a result of differentiation. When differentiation isused, however, a noise component is naturally increased. In an opticaldisc medium having an inferior S/N ratio, a detection error isreasonably expected. In this example, each pattern of the wobbles 826and 827 is repeated a plurality of times in order to enhance thereliability of detection.

Main information is recorded in a block unit 841 along the track groove802 from the block mark 810. The block unit 841 has a prescribed length,for example, 64 kB (or 32 kB). The main information can be recorded asrecording marks 28. A block unit is a unit for information processing,and is, for example, an ECC block. The block unit 841 is divided into 32sectors 825 when N=32 (or 16 sectors 825 when N=16). Each sector 25 is asub block having a length of 2 kB. Each sector 25 is divided into 26frames #0 through #25 when M=26. At a leading end of each of frames #0through #25, a SYNC mark is recorded as a synchronization signal usedfor reproducing data.

A frame is a fundamental unit of information recorded on the trackgroove 802. In FIG. 8, frame #0 is represented by reference numeral 822and frame #1 is represented by reference numeral 823. As exemplified bythe frames 822 and 823, each frame includes one type of wobbles formedin a periodical manner in advance. In this way, 1-bit sub information“0”, “1” or “S” is described in each of the frames 822 and 823. A 26-bit(M=26) sub information group included in each sector 825 indicates atleast a portion of a block ID (address information) of the correspondingblock unit 841.

One bit information is assigned to each of frames #0 through #25. Forexample, 8 frames (i.e., 8 bits) are assigned as a 1-byte portion of theblock ID. The following 8 frames are assigned as a 1-byte parity of theblock ID. The following 5 frames are assigned as a 5-bit byte sectornumber. The remaining 5 frames are assigned as a 5-bit parity of thesector number. The sector number indicates the order of the sector amongthe plurality of sectors (i.e., the fifth sector, tenth sector or thelike). Each parity indicates at least one of an error detection code oran error correction code.

The sub information for one sector assigned as described above isarranged, for example, over 4 sectors 825 (i.e., a sector group 825′).By arranging a portion of the block ID, i.e., 1 bytes for each of the 4sectors, a 32-bit block ID (8 bits×4=32 bits) can be represented.

FIG. 10 shows an exemplary format of the sub information recorded in thesectors 825 in the block unit 841 and frames #0 through #25. In FIG. 10,the leftmost section shows the sector numbers. To the right thereof, thesub information recorded in the frames of each sector is shown. It isassumed that the block unit 841 includes 32 sectors. The sector numbersin parentheses “( )” are the sector numbers in the case where the blockunit 841 includes 16 sectors. Each of frames #0 through #25 includes1-bit sub information. In this example, the block unit 841 is an ECCblock.

The contents of sector 0 will be described. Among frames #0 through #25of sector 0, in frames #0 through #7, the first 1 byte among the 4 bytes(32 bits) of the ECC block address is buried sequentially from the LSB.In frames #8 through #15, the sub information of the first 1 byte amongthe 4 bytes of the parity of the ECC block address is buried. In frames#16 through #20, 5-bit sub information representing the sector number isburied. In frames #21 through #25, 5-bit sub information representingthe parity of the sector number is buried. As shown in FIG. 8, in sector0, 1-byte “01h” is buried as a portion of the block ID.

The contents of sector 1 will be described. Among frames #0 through #25of sector 1, in frames #0 through #7, the second 1 byte among the 4bytes (32 bits) of the ECC block address is buried sequentially from thelowest bit. In frames #8 through #15, the sub information of the second1 byte among the 4 bytes of the parity of the ECC block address isburied. In frames #16 through #20, 5-bit sub information representingthe sector number is buried. In frames #21 through #25, 5-bit subinformation representing the parity of the sector number is buried. Asshown in FIG. 8, in sector 1, 1-byte “23h” is buried as a portion of theblock ID.

The contents of sector 2 will be described. Among frames #0 through #25of sector 2, in frames #0 through #7, the third 1 byte among the 4 bytes(32 bits) of the ECC block address is buried sequentially from thelowest bit. In frames #8 through #15, the sub information of the third 1byte among the 4 bytes of the parity of the ECC block address is buried.In frames #16 through #20, 5-bit sub information representing the sectornumber is buried. In frames #21 through #25, 5-bit sub informationrepresenting the parity of the sector number is buried. As shown in FIG.8, in sector 2, 1-byte “45h” is buried as a portion of the block ID.

The contents of sector 3 will be described. Among frames #0 through #25of sector 3, in frames #0 through #7, the fourth 1 byte among the 4bytes (32 bits) of the ECC block address is buried sequentially from thelowest bit. In frames #8 through #15, the sub information of the fourth1 byte among the 4 bytes of the parity of the ECC block address isburied. In frames #16 through #20, 5-bit sub information representingthe sector number is buried. In frames #21 through #25, 5-bit subinformation representing the parity of the sector number is buried. Asshown in FIG. 8, in sector 3, 1-byte “67h” is buried as a portion of theblock ID.

In this manner, a 32-bit block ID “76543210h” is represented bycombining 1-byte information from each of the 4 sectors 825.

The 4 byte block ID in the sectors 825 is preferably arranged in areading order, i.e., sequentially from the first sector 825 to be readto the last sector 825 to be read, and from the lowest bit to thehighest bit of the block ID.

The contents of sectors 4 et seq. will be described. In sectors 4through 7, the contents of sectors 0 through 3 are described inrepetition. Similarly, in sectors 8 through 11, 12 through 15, 16through 19, 20 through 23, 24 through 27, and 28 through 31, thecontents of sectors 0 through 3 are described in repetition.

In this manner, the information in 4 sectors is described 8 times (4times when the block unit 841 includes 16 sectors). Thus, parityinformation for realizing error correction can be added to each blockunit 841. The reading reliability of the block ID can be enhanced.

Since the sector numbers are described, even when 1 byte of the block IDis missing, the 1 byte which is missing can be identified easily byreading the sector number. Thus, the reading reliability of the block IDcan be enhanced.

Since the sector numbers are described, the following advantage isprovided. When the data is not continuously read, for example, after aseek operation, the sector number of the sector 825 immediately afterthe seek operation can be read, instead of reading the block unit 841from the block mark 810 at the leading end. Due to such an operation,the block ID can be finally determined by reading the sub information ofthe 4 sectors 825 starting from an arbitrary sector 825.

Since the block ID is finally determined by reading only any one ofsector groups 825′ each including 4 sectors (8 kB=2 kB×4),post-processing (data read, data recording, etc.) can be performedquickly.

Even when about 4 sectors of the block ID are incorrectly read due to adisc scratch (defect), the correct block ID can be read by the sectorgroup with no defect. Thus, a significantly high level of reliability ofreading the block ID is guaranteed.

Instead of the sector number, an ID number indicating the order of thesector among the 4 sector 825 (i.e., the first sector, second sector, orthe like) in one sector group 825′ can be described. Whereas FIG. 10shows the 5-bit sector number and the 5-bit parity of the sector numberin frames #16 through #25, FIG. 16 shows a 2-bit ID number, a 2-bitparity of the ID number, and a 6-bit order number of the repeated blockID, indicating the order of the repeated block ID, in frames #16 through#25.

When the ID numbers are used, 5-bit sub information required for eachsector number can be reduced to 2-bits. Using the remaining 8 bits(frames #18 through #25), the error correction ability for the IDnumbers can be improved, or the order number of the block ID can bedescribed.

Since the ID numbers are described, the following advantage is provided.When the data is not continuously read, for example, after a seekoperation, the ID number of the sector 825 immediately after the seekoperation can be read, instead of reading the block unit 841 from theblock mark 810 at the leading end. Due to such an operation, the blockID can be finally determined by reading the sub information of the 4sectors 825 starting from an arbitrary sector 825.

In the case where the sub information includes the order number of theblock ID, the order number can be used for finally determining theaddress number based on a majority. In addition, such a number providesuseful information for signal processing, for example, which sector 825in the block is now read or which sub information group in the block isincorrect.

In the case of an optical disc medium having a plurality of recordingfaces or layers, an order number of the recording layer can be includedin the sub information group. In this way, the recording face can beeasily identified. For example, one of the four same order numbers inFIG. 16 can be replaced with the order number of the recording layer.Thus, the recording face can be easily identified.

In this example, the block ID has 32 bits. The number of bits of theaddress information is not limited to 32, but can be any necessarynumber in accordance with, for example, the data amount to be recordedon the optical disc medium or the type and system of the errorcorrection code.

In this example, the block unit is divided into 32 sectors with N=32 (or16 sectors with N=16). The present invention is not limited to such anumber of sectors.

In this example, the sub information is recorded in 26 frames includedin each sector with M=26. The present invention is not limited to such anumber of frames.

In this example, the sub information is recorded after being modulatedinto sawtooth-shaped wobbles. The present invention is not limited tosuch a shape of wobbles. The sub information can be recorded after beingmodulated into wobbles having a shape, for example, shown in FIG. 4 or7.

In this example, the block mark is a cut-off portion of the trackgroove. The present invention is not limited to such a form of blockmark. For example, the block mark can be modulated into wobbles having ashape, for example, shown in FIG. 5 or 6.

EXAMPLE 8

FIG. 11 shows a track groove 1102 according to Example 8 of the presentinvention. The track groove 1102 can be formed in the optical discmedium 20 shown in FIG. 2 instead of the track groove 102 shown inFIG. 1. As shown in FIG. 11, the track groove 1102 has shapes which aredifferent on a block-by-block basis. In FIG. 11, a block mark(identification mark) 1110 is a cut-off portion in the track groove 1102and shows an index indicating a leading end of each block.

Each block is divided into N number of sectors 1125 (N=32 or 16), andeach sector 1125 is divided into M number of frames #0 through #25(M=26). Each frame has a prescribed number of wobbles 1126 or 1127 in aperiodical manner. The wobbles 1126 and 1127 have different prescribedshapes from each other, and represent sub information (“0”, “1” or “S”).One type of sub information (“0”, “1” or “S”) is represented by oneshape of wobbles 1126 or 1127. The type of sub information and the shapeof wobbles (wobbles 1126 or 1127) are in a one-to-one relationship. Morespecifically, the wobbles 1126 and 1127 both have a generally sawtoothshape, and have different rising shapes (or rising gradient) and fallingshapes (falling gradients). The wobbles 1126 or 1127 are formed inaccordance with the type of sub information (“0” or “1”). A string ofsub information is represented by a combination of the wobbles 1126 and1127.

The difference in the rising gradient and the falling gradient betweenthe wobbles 1126 and 1127 can be easily detected by a differentialpush-pull detection signal as follows. A scanning laser beam is directedto the track groove 1102, and a differential signal indicating thedifference between the light amounts received by detection areas of alight receiving element divided along a direction perpendicular to thetrack groove 1102 (a radial direction) of the optical disc medium 20(i.e., a push-pull signal) is generated. Thus, a detection signal havinga rising gradient and a falling gradient which vary in accordance withwhether the sub information is “0” or “1” is obtained. This differencein the rising gradient and the falling gradient can be easily identifiedby, for example, differentiating the detection signal.

Thus, the type of the sub information can be detected by the size of thevalue obtained as a result of differentiation. When differentiation isused, however, a noise component is naturally increased. In an opticaldisc medium having an inferior S/N ratio, a detection error isreasonably expected. In this example, each pattern of the wobbles 1126and 1127 is repeated a plurality of times in order to enhance thereliability of detection.

Main information is recorded in a block unit 1141 along the track groove1102 from the block mark 1110. The block unit 1141 has a prescribedlength, for example, 64 kB (or 32 kB). The main information can berecorded as recording marks 28. A block unit is a unit for informationprocessing, and is, for example, an ECC block. The block unit 1141 isdivided into 32 sectors 1125 when N=32 (or 16 sectors 1125 when N=16).Each sector 1125 is a sub block having a length of 2 kB. Each sector1125 is divided into 26 frames #0 through #25 when M=26. At a leadingend of each of frames #0 through #25, a SYNC mark is recorded as asynchronization signal used for reproducing data.

A frame is a fundamental unit of information recorded on the trackgroove 1102. In FIG. 11, frame #0 is represented by reference numeral1122 and frame #1 is represented by reference numeral 1123. Asexemplified by the frames 1122 and 1123, each frame includes one type ofwobbles formed in a periodical manner in advance. In this way, 1-bit subinformation “0”, “1” or “S” is described in each of the frames 1122 and1123. A 26-bit (M=26) sub information group included in each sector 1125indicates at least a portion of a block ID (address information) of thecorresponding block unit 1141.

The block ID can include an error correction code, an error detectioncode, or a parity code or the like for correcting or detecting detectionsignals, in addition to the information indicating the address.

The 26 frames in each sector 1125 are divided into, for example, first13 frames (frames #0 through #12; first frame group) and second 13frames (frames #13 through 25; second frame group). 1-bit subinformation is recorded in every 13 frames as a portion of the block ID.Thus, 2-bit sub information is recorded in each sector 1125 as a portionof the block ID.

FIG. 12 shows an exemplary format of the sub information recorded in thesectors 1125 in the block unit 1141 and frames #0 through #25. In FIG.12, the leftmost section shows the sector numbers. To the right thereof,the sub information recorded in the frames of each sector is shown.1-bit sub information is recorded in the first 13 frames, and 1-bit subinformation is recorded in the second 13 frames (frame group). In thisexample, the block unit 1141 is an ECC block. B0 through B31 eachindicate the order number of the bit (i.e., whether the correspondingbit is the first bit, the second bit, etc.) in the ECC block address.

The contents of sector 0 will be described. Among frames #0 through #25of sector 0, in frames #0 through #12 (first frames), the first 1 bitamong the 32 bits of the ECC block address (LSB) is buried. In frames#13 through #25 (second frames), the sub information of the second 1 bitamong the 32 bits of the ECC block address is buried. As shown in FIG.11, in sector 0, 2-bit information (“0” and “1”) is buried as a portionof the block ID.

In the first frames of sector 0, a SYNC code “S” indicating the start ofthe ECC block address can be buried instead of the first 1 bit of theECC block address (LSB). The SYNC code “S” can be used as asynchronization signal for reproducing the ECC block address or as adetection mark for detecting the start of the ECC block address.

The contents of sector 1 will be described. Among frames #0 through #25of sector 1, in frames #0 through #12, the third 1 bit among the 32 bitsof the ECC block address is buried. In frames #13 through #25, the subinformation of the fourth 1 byte among the 32 bits of the ECC blockaddress is buried. As shown in FIG. 11, in sector 1, 2-bit information(“0” and “1”) is buried as a portion of the block ID.

In this manner, a 32-bit block ID is represented by combining 2-bitinformation from each of the 16 sectors 1125.

In the case where the ECC block has a length of 32 kB and the one blockunit 1141 is divided into 16 sectors 1125, a 32-bit block can beobtained by recording 2-bit sub information in each sector 1125.

In the case where the ECC block has a length of 32 kB, one block ID isrepresented by 16 sectors as described above. In the case where the ECCblock has a length of 64 kB, one block unit 1141 has 32 sectors 1125. Insectors 16 through 31, the contents of sectors 0 through 15 aredescribed in repetition. Namely, the information in 16 sectors (subinformation group) is described twice.

Since the sub information is recorded in repetition in the block unit1141, the block ID is finally determined by reading only 16 sectors,i.e., 32 kB (2 kB×16). Therefore, post-processing (data read, datarecording, etc.) can be performed quickly. Since the block ID isrepeated twice in the block unit 1141, the reading reliability of theblock ID can be enhanced.

Instead of recording the block ID in the block unit 1141 twice,information other than the block ID can be included. For example, theorder number of the block ID can be included in the sub informationgroup. The order number can be used for finally determining the addressnumber based on a majority. In addition, such a number provides usefulinformation for signal processing, for example, which sector 1125 in theblock is now read or which sub information group in the block isincorrect.

In the case of an optical disc medium having a plurality of recordingfaces or layers, an order number of the recording layer can be includedin the sub information group. In this way, the recording face can beeasily identified as described above with reference to FIG. 16.

In this example, the block ID has 32 bits. The number of bits of theaddress information is not limited to 32, but can be any necessarynumber in accordance with, for example, the data amount to be recordedon the optical disc medium or the type and system of the errorcorrection code.

In this example, the block unit is divided into 32 sectors with N=32 (or16 sectors with N=16). The present invention is not limited to such anumber of sectors.

In this example, the sub information is recorded in 26 frames includedin each sector with M=26. The present invention is not limited to such anumber of frames.

In this example, the sub information is recorded after being modulatedinto sawtooth-shaped wobbles. The present invention is not limited tosuch a shape of wobbles. The sub information can be recorded after beingmodulated into wobbles having a shape, for example, shown in FIG. 4 or7.

In this example, the block mark is a cut-off portion of the trackgroove. The present invention is not limited to such a form of blockmark. For example, the block mark can be modulated into wobbles having ashape, for example, shown in FIG. 5 or 6.

EXAMPLE 9

FIG. 13 shows a track groove 1302 according to Example 9 of the presentinvention. The track groove 1302 can be formed in the optical discmedium 20 shown in FIG. 2 instead of the track groove 102 shown inFIG. 1. As shown in FIG. 13, the track groove 1302 has shapes which aredifferent on a block-by-block basis. In FIG. 13, a block mark(identification mark) 1310 is a cut-off portion in the track groove 1302and shows an index indicating a leading end of each block.

Each block is divided into N number of sectors 1325 (N=32 or 16), andeach sector 1325 is divided into M number of frames #0 through #25(M=26). Each frame has a prescribed number of wobbles 1326 or 1327 in aperiodical manner. The wobbles 1326 and 1327 have different prescribedshapes from each other, and represent sub information (“0”, “1” or “S”).One type of sub information (“0”, “1” or “S”) is represented by oneshape of wobbles 1326 or 1327. The type of sub information and the shapeof wobbles (wobbles 1326 or 1327) are in a one-to-one relationship. Morespecifically, the wobbles 1326 and 1327 both have a generally sawtoothshape, and have different rising shapes (or rising gradient) and fallingshapes (falling gradients). The wobbles 1326 or 1327 are formed inaccordance with the type of sub information (“0” or “1”). A string ofsub information is represented by a combination of the wobbles 1326 and1327.

The difference in the rising gradient and the falling gradient betweenthe wobbles 1326 and 1327 can be easily detected by a differentialpush-pull detection signal as follows. A scanning laser beam is directedto the track groove 1302, and a differential signal indicating thedifference between the light amounts received by detection areas of alight receiving element divided along a direction perpendicular to thetrack groove 1302 (a radial direction) of the optical disc medium 20(i.e., a push-pull signal) is generated. Thus, a detection signal havinga rising gradient and a falling gradient which vary in accordance withwhether the sub information is “0” or “1” is obtained. This differencein the rising gradient and the falling gradient can be easily identifiedby, for example, differentiating the detection signal.

Thus, the type of the sub information can be detected by the size of thevalue obtained as a result of differentiation. When differentiation isused, however, a noise component is naturally increased. In an opticaldisc medium having an inferior S/N ratio, a detection error isreasonably expected. In this example, each pattern of the wobbles 1326and 1327 is repeated a plurality of times in order to enhance thereliability of detection.

Main information is recorded in a block unit 1341 along the track groove1302 from the block mark 1310. The block unit 1341 has a prescribedlength, for example, 64 kB (or 32 kB). The main information can berecorded as recording marks 28. A block unit is a unit for informationprocessing, and is, for example, an ECC block. The block unit 1341 isdivided into 32 sectors 1325 when N=32 (or 16 sectors 1325 when N=16).Each sector 1325 is a sub block having a length of 2 kB. Each sector1325 is divided into 26 frames #0 through #25 when M=26. At a leadingend of each of frames #0 through #25, a SYNC mark is recorded as asynchronization signal used for reproducing data.

A frame is a fundamental unit of information recorded on the trackgroove 1302. In FIG. 13, frame #0 is represented by reference numeral1322 and frame #1 is represented by reference numeral 1323. Asexemplified by the frames 1322 and 1323, each frame includes one type ofwobbles formed in a periodical manner in advance. In this way, 1-bit subinformation “0”, “1” or “S” is described in each of the frames 1322 and1323. A 26-bit (M=26) sub information group included in each sector 1325indicates at least a portion of a block ID (address information) of thecorresponding block unit 1341.

The 26 frames in each sector 1325 are divided into, for example, first13 frames (frames #0 through #12; first frame group) and second 13frames (frames #13 through #25; second frame group). In the 13 frames inthe first frames, the same shape of wobbles are formed in a periodicalmanner in advance. In the 13 frames in the second frames, the same shapeof wobbles are formed in a periodical manner in advance. Thus, 2-bit subinformation “0”, “1” or “S” is described in each sector 1325. 32-bit subinformation in each sector 1325 indicates at least a portion of a blockID (address information) of the corresponding block unit 1341.

The block ID can include an error correction code, an error detectioncode, or a parity code or the like for correcting or detecting detectionsignals, in addition to the information indicating the address.

FIG. 14 shows an exemplary format of the sub information recorded in thesectors 1325 in the block unit 1341 and frames #0 through #25. In FIG.14, the leftmost section shows the sector numbers. To the right thereof,the sub information recorded in the frames of each sector is shown.

The contents of sector 0 will be described. In all frames #0 through #25of sector 0, the first 1 bit among the 32 bits of the ECC block address(LSB) is buried. As shown in FIG. 14, in sector 0, 1-bit sub informationB0 (“0” or “1”) is buried.

The contents of sector 1 will be described. In all frames #0 through #25of sector 1, the first 1 bit among the 32 bits of the ECC block address(LSB) is buried. As shown in FIG. 14, in sector 1, 1-bit sub informationB0 (“0” or “1”) is buried.

In sector 1, the sub information B0 buried in sector 0 is described inrepetition.

The contents of sector 2 will be described. In all frames #0 through #25of sector 2, the second 1 bit among the 32 bits of the ECC block addressis buried. As shown in FIG. 14, in sector 2, 1-bit sub information B1(“0” or “1”) is buried.

The contents of sector 3 will be described. In all frames #0 through #25of sector 3, the second 1 bit among the 32 bits of the ECC block addressis buried. As shown in FIG. 14, in sector 3, 1-bit sub information B1(“0” or “1”) is buried.

In sector 3, the sub information B1 buried in sector 2 is described inrepetition.

In this manner, in even number sectors up to sector 12, third, fourth,fifth, sixth and seventh 1 bit among the 32 bits of the ECC blockaddress are respectively buried. In the odd number (N) sectors up tosector 13, the same sub information as in the even-number (N−1) sectorsis buried.

The contents of sectors 14 through 24 will be described.

The contents of sector 14 will be described. In all frames #0 through#25 of sector 14, the eighth 1 bit among the 32 bits of the ECC blockaddress is buried. As shown in FIG. 14, in sector 14, 1-bit subinformation B7 (“0” or “1”) is buried.

The contents of sector 15 will be described. In all frames #0 through#25 of sector 15, the ninth 1 bit among the 32 bits of the ECC blockaddress is buried. As shown in FIG. 14, in sector 15, 1-bit subinformation B8 (“0” or “1”) is buried.

1-bit sub information is described up to sector 24 similarly.

The contents of sectors 25 through 31 will be described.

The contents of sector 25 will be described. Among frames #0 through #25of sector 25, in frames #0 through #12 (first frame group), the 19th 1bit among the 32 bits of the ECC block address is buried. As shown inFIG. 14, in the first frame group of sector 25, 1-bit sub informationB18 (“0” or “1”) is buried.

Among frames #0 through #25 of sector 25, in frames #13 through #25(second frame group), the 20th 1 bit among the 32 bits of the ECC blockaddress is buried. As shown in FIG. 14, in the second frame group ofsector 25, 1-bit sub information B19 (“0” or “1”) is buried.

The contents of sector 26 will be described. Among frames #0 through #25of sector 26, in frames #0 through #12 (first frame group), the 21st 1bit among the 32 bits of the ECC block address is buried. As shown inFIG. 14, in the first frame group of sector 26, 1-bit sub informationB20 (“0” or “1”) is buried.

Among frames #0 through #25 of sector 26, in frames #13 through #25(second frame group), the 22nd 1 bit among the 32 bits of the ECC blockaddress is buried. As shown in FIG. 14, in the second frame group ofsector 26, 1-bit sub information B21 (“0” or “1”) is buried.

1-bit sub information is described up to sector 31 similarly.

As described above, in this example, the number of sectors and thenumber of frames in which the sub information is described are varied inaccordance with the position of the bit of the block ID (i.e., lower bitor higher bit). In this example, sub information B0 is the LSB and thesub information B31 is the HSB.

In a system for reading continuous data stored in, for example, anoptical disc, the block ID of data which is being continuously readincreases from a lower bit sequentially. Between two adjacent block IDs,the block ID value is different only by “1”. Therefore, the block ID canbe determined merely by reading several lower bits of the block ID whichis being read, since the remaining higher bits can be estimated from thevalue which is read from the immediately previous block ID or from thevalue which is read from the block ID previous to the current block IDby a certain number. In this case, the reading reliability of theseveral lower bits of the block ID is important. In this example, thelower bits of the block ID is arranged over a plurality of sectors,i.e., by a larger number than the other higher bits as shown in FIG. 14.Therefore, the reading reliability of the lower bits of the block ID,and thus the reading efficiency of the block ID can be enhanced.

In this example, the block ID has 32 bits. The number of bits of theaddress information is not limited to 32, but can be any necessarynumber in accordance with, for example, the data amount to be recordedon the optical disc medium or the type and system of the errorcorrection code.

In this example, the block unit is divided into 32 sectors with N=32 (or16 sectors with N=16). The present invention is not limited to such anumber of sectors.

In this example, the sub information is recorded in 26 frames includedin each sector with M=26. The present invention is not limited to such anumber of frames.

In this example, the sub information is recorded after being modulatedinto sawtooth-shaped wobbles. The present invention is not limited tosuch a shape of wobbles. The sub information can be recorded after beingmodulated into wobbles having a shape, for example, shown in FIG. 4 or7.

In this example, the block mark is a cut-off portion of the trackgroove. The present invention is not limited to such a form of blockmark. For example, the block mark can be modulated into wobbles having ashape, for example, shown in FIG. 5 or 6.

EXAMPLE 10

FIG. 15 shows a track groove 1502 according to Example 10 of the presentinvention. The track groove 1502 can be formed in the optical discmedium 20 shown in FIG. 2 instead of the track groove 102 shown inFIG. 1. As shown in FIG. 15, the track groove 1502 has shapes which aredifferent on a block-by-block basis. In FIG. 15, a block mark(identification mark) 1510 is a cut-off portion in the track groove 1502and shows an index indicating a leading end of each block.

Each block is divided into N number of sectors 1525 (N=32 or 16), andeach sector 1525 is divided into M number of frames #0 through #25(M=26). Each frame has a prescribed number of wobbles 1526 or 1527 in aperiodical manner. The wobbles 1526 and 1527 have different prescribedshapes from each other, and represent sub information (“0”, “1” or “S”).One type of sub information (“0”, “1” or “S”) is represented by oneshape of wobbles 1526 or 1527. The type of sub information and the shapeof wobbles (wobbles 1526 or 1527) are in a one-to-one relationship. Morespecifically, the wobbles 1526 and 1527 both have a generally sawtoothshape, and have different rising shapes (or rising gradient) and fallingshapes (falling gradients). The wobbles 1526 or 1527 are formed inaccordance with the type of sub information (“0” or “1”). A string ofsub information is represented by a combination of the wobbles 1526 and1527.

The difference in the rising gradient and the falling gradient betweenthe wobbles 1526 and 1527 can be easily detected by a differentialpush-pull detection signal as follows. A scanning laser beam is directedto the track groove 1502, and a differential signal indicating thedifference between the light amounts received by detection areas of alight receiving element divided along a direction perpendicular to thetrack groove 102 (a radial direction) of the optical disc medium 20(i.e., a push-pull signal) is generated. Thus, a detection signal havinga rising gradient and a falling gradient which vary in accordance withwhether the sub information is “0” or “1” is obtained. This differencein the rising gradient and the falling gradient can be easily identifiedby, for example, differentiating the detection signal.

Thus, the type of the sub information can be detected by the size of thevalue obtained as a result of differentiation. When differentiation isused, however, a noise component is naturally increased. In an opticaldisc medium having an inferior S/N ratio, a detection error isreasonably expected. In this example, each pattern of the wobbles 1526and 1527 is repeated a plurality of times in order to enhance thereliability of detection.

Main information is recorded in a block unit 1541 along the track groove1502 from the block mark 1510. The block unit 1541 has a prescribedlength of, for example, 64 kB (or 32 kB). The main information can berecorded as recording marks 28. A block unit is a unit for informationprocessing, and is, for example, an ECC block. The block unit 1541 isdivided into 32 sectors 1525 when N=32 (or 16 sectors 1525 when N=16).Each sector 1525 is a sub block having a length of 2 kB. Each sector1525 is divided into 26 frames #0 through #25 when M=26. At a leadingend of each of frames #0 through #25, a SYNC mark is recorded as asynchronization signal used for reproducing data.

A frame is a fundamental unit of information recorded on the trackgroove 1502. In FIG. 15, frame #0 is represented by reference numeral1522 and frame #1 is represented by reference numeral 1523. Asexemplified by the frames 1522 and 1523, each frame includes one type ofwobbles formed in a periodical manner in advance. In this way, 1-bit subinformation “0”, “1” or “S” is described in each of the frames 1522 and1523. The sub information is described as SYNC information. A 26-bit(M=26) sub information group included in each sector 1525 indicates atleast a portion of a block ID (address information) of the correspondingblock unit 1541.

1-bit sub information is assigned to one frame, and thus a 32-bit blockID is buried in the continuous 32 frames (sub information group).

The block ID can include an error correction code, an error detectioncode, or a parity code or the like for correcting or detecting detectionsignals, in addition to the information indicating the address.

As described above, a block ID is represented by combining 1-bitinformation, which is assigned to each of the 32 frames. Namely, theentire block ID is represented by the 32-bit sub information group.

When the ECC block has a length of 64 kB, each block includes 32sectors. Accordingly, one block includes 832 frames (=32×26). When theblock ID is represented by 32 frames (one frame group), the block ID canbe repeated 26 times (i.e., the same block ID is described in 26 framegroups) in the block unit 1541.

When the ECC block has a length of 32 kB, each block includes 16sectors. Accordingly, one block includes 416 frames (=16×26). When theblock ID is represented by 32 frames (one frame group), the block ID canbe repeated 13 times (i.e., the same block ID is described in 13 framegroups) in the block unit 1541.

In this manner, the block ID is represented by 32 frames (one framegroup), and the ID block is described a plurality of times in the blockunit 1541.

Thus, the block ID is finally determined by reading only 32 frames.Therefore, post-processing (data read, data recording, etc.) can beperformed quickly.

Since the block ID is repeated a plurality of times in the block unit1541, the reading reliability of the block ID can be enhanced.

Information other than the block ID can be included as described abovewith reference to FIG. 16 although the times of repeating the block IDin the block unit 1541 is reduced in this case. For example, the ordernumber of the block ID can be included in the sub information group. Theorder number can be used for finally determining the address numberbased on a majority. In addition, such a number provides usefulinformation for signal processing, for example, which sector 1525 in theblock is now read or which sub information group in the block isincorrect.

In the case of an optical disc medium having a plurality of recordingfaces or layers, an order number of the recording layer can be includedin the sub information group. In this way, the recording face can beeasily identified. For example, one of the four same order numbers inFIG. 16 can be replaced with the order number of the recording layer.Thus, the recording face can be easily identified.

In this example, the block ID has 32 bits. The number of bits of theaddress information is not limited to 32, but can be any necessarynumber in accordance with, for example, the data amount to be recordedon the optical disc medium or the type and system of the errorcorrection code.

In this example, the block unit is divided into 32 sectors with N=32 (or16 sectors with N=16). The present invention is not limited to such anumber of sectors.

In this example, the sub information is recorded in 26 frames includedin each sector with M=26. The present invention is not limited to such anumber of frames.

In this example, the sub information is recorded after being modulatedinto sawtooth-shaped wobbles. The present invention is not limited tosuch a shape of wobbles. The sub information can be recorded after beingmodulated into wobbles having a shape, for example, shown in FIG. 4 or7.

In this example, the block mark is a cut-off portion of the trackgroove. The present invention is not limited to such a form of blockmark. For example, the block mark can be modulated into wobbles having ashape, for example, shown in FIG. 5 or 6.

EXAMPLE 11

FIG. 22 shows a track groove 1602 according to Example 11 of the presentinvention. The track groove 1602 can be formed in the optical discmedium 20 shown in FIG. 2 instead of the track groove 102 shown inFIG. 1. As shown in FIG. 22, the track groove 1602 has shapes which aredifferent on a block-by-block basis.

Referring to FIG. 22, an ECC block which is a unit of forming a blockaddress is divided into four PID sections PID0 through PID3. The PIDsections PID0, PID1, PID2 and PID3 are respectively indicated byreference numerals 2202, 2204, 2206 and 2208. The PID section 2202,2204, 2206 and 2208 are respectively preceded by annex sections 0through 3. The annex sections 0, 1, 2 and 3 are respectively indicatedby reference numerals 2201, 2203, 2205 and 2207. The annex sections2201, 2203, 2205 and 2207 each include a block mark (identificationmark) 2220. In FIG. 22, a block mark (identification mark) 2220 is acut-off portion in the track groove 1602 and shows an index indicating aleading end of each PID section.

As described above, the block is divided into four PID sections (N=4),and each PID section is further divided into M number of frames (M=52).Each frame (e.g., each of frames 2222, 2223, 2224 and 2225) has aprescribed number of wobbles 2226, 2227, 2229 or 2230 along the trackgroove 1602 from the block mark 2220. The wobbles 2226, 2227, 2229 and2230 have different prescribed shapes from each other, and represent subinformation (“0”, “1”, “S” or “B”). One type of sub information (“0”,“1”, “S” or “B”) is represented by one shape of wobbles 2226, 2227, 2229or 2230. The type of sub information and the shape of wobbles (wobbles2226, 2227, 2229 or 2230) are in a one-to-one relationship. Morespecifically, the wobbles 2226, 2227 and 2228 all have a generallysawtooth shape, and the wobble 2230 has a sine wave shape. The wobbles2226, 2227, 2228 and 2230 have different rising shapes (or risinggradient) and falling shapes (falling gradients). The wobbles 2226,2227, 2229 or 2230 are formed in accordance with the type of subinformation (“0”, “1”, “S” or “B”).

The difference in the rising gradient and the falling gradient among thewobbles 2226, 2227, 2229 and 2230 can be easily detected by adifferential push-pull detection signal as follows. A scanning laserbeam is directed to the track groove 1602, and a differential signalindicating the difference between the light amounts received bydetection areas of a light receiving element divided along a directionperpendicular to the track groove 1602 (a radial direction) of theoptical disc medium 20 (i.e., a push-pull signal) is generated. Thus, adetection signal having a rising gradient and a falling gradient whichvary in accordance with whether the sub information is “0”, “1”, “S” or“B” is obtained. This difference in the rising gradient and the fallinggradient can be easily identified by, for example, differentiating thedetection signal.

Thus, the type of the sub information can be detected by the size of thevalue obtained as a result of differentiation. When differentiation isused, however, a noise component is naturally increased. In an opticaldisc medium having an inferior S/N ratio, a detection error isreasonably expected. In this example, each pattern of the wobbles 2226,2227, 2229 and 2230 is repeated a plurality of times in order to enhancethe reliability of detection.

The contents of the PID sections will be described. Each PID sectionincludes 52 frames each having 372 bytes, and thus has a length of 19344bytes (=372 bytes×52). The PID section 2202 (PID0) includes 8-bit PIDinformation 2209, 24-bit block address information 2210, 16-bit IEDinformation 2211, and a 4-bit address mark (AM) 2212.

The PID information 2209 represents the number of the corresponding PIDsection (i.e., whether the PID section is PID0, PID1, PID2 or PID3). Theblock address information 2210 is address information assigned to eachblock, and is common among PID0 through PID3 of the same ECC block. TheIED information 2211 is an ID error detection code generated from thePID information 2209 and the block address information 2210.

The address mark 2212 is located at a trailing end of the PID section2202 (trailing end) and is used for detecting a leading end of the PIDsection 2204, which is immediately subsequent to the PID section 2202.The address mark 2211 includes sub information “B” using sinewave-shaped wobbles such as, for example the wobbles 2230 in the frame2225 in addition to the sub information “1”, “0”, or “S”. The addressmark 2212 is represented by combining the sub information “S” recordedby the wobbles 2229 in the frame 2224 and the sub information “B”. Forexample, the address mark 2212 has 4-bit information “SBBS”. When thispattern is detected, detection of the following annex section or PIDsection is prepared for.

Since the sub information “B” is used only for the address mark, theaddress mark is easily be distinguishable from the sections having otherinformation. Thus, the detection precision of the address mark can beenhanced.

The contents of the annex sections will be described. Unlike the PIDsections, each annex section has the block mark 2220 recorded on thedisc in advance. The block mark 2220 is, for example, a mirror markwhich is a cut-off portion in the track groove 1602 as shown in FIG. 17described below. The annex section 2201 precedes the PID section 2202(PID0) and is also a leading end of the ECC block.

Annex sections 0 through 3 are provided in advance before PID0 throughPID3, respectively, and each have a length of 93 bytes. The block mark(mirror mark) 2220 has a length of about 2 bytes. In each annex section,dummy data can be recorded in order to enhance the detecting precisionof the block mark 2220.

Usable dummy data can be, for example, information including 4T marksand 4T spaces simply in repetition. Thus, the recording mark of thesingle frequency component and the block mark can be frequency-separatedfor easier detection. Thus, the block mark can be more easily detected.

As described above, one ECC block is divided into four PID sections, andeach PID section is preceded by an annex section. In each annex section,a block mark indicating a leading end of the PID section is formed. SuchPID sections are repeated in the ECC block. Since the block ID isfinally determined by reading only ¼ of the ECC block, post-processing(data read, data recording, etc.) can be performed quickly.

Since the block ID is repeated a plurality of times in the ECC block,the reading reliability of the block ID can be enhanced.

In this example, one ECC block is divided into four PID sections. Thepresent invention is not limited to such a number of PID sections. OneECC block can be divided into an arbitrary integral number of PIDsections.

In this example, the sub information is recorded after being modulatedinto sawtooth-shaped wobbles. The present invention is not limited tosuch a shape of wobbles. The sub information can be recorded after beingmodulated into wobbles having a shape, for example, shown in FIG. 4 or7.

In this example, the block mark is a cut-off portion of the trackgroove. The present invention is not limited to such a form of blockmark. For example, the block mark can be modulated into wobbles having ashape, for example, shown in FIG. 5 or 6. Alternatively, the block markcan be modulated into wobbles having a shape, for example, shown in FIG.17, 18 or 19.

EXAMPLE 12

FIG. 17 shows a track groove 1702 according to Example 12 of the presentinvention. The track groove 1702 is obtained by modifying the annexsection of the track groove 1602 shown in FIG. 22.

In FIG. 17, reference numeral 1701 represents annex section 0, and 1705represents each of annex sections 1 through 3. The track groove 1702having a shape of a continuous plurality of sine wave-like wobbles isformed in the disc in advance, and each annex section has a length of 93bytes. The annex section includes nine wobbles. Annex section 0 hasblock marks 1703 and 1704 each as a cut-off portion of the track groove1702, and annex sections 1 through 3 each have a block mark 1706 as acut-off portion of the track groove 1702.

As described in Example 11, annex sections 0 through 3 precederespective PID sections and can be a leading end of the addressinformation. Therefore, it is demanded to provide a satisfactorily highlevel of reading reliability of annex sections 0 through 3. In the casewhere the block mark is repeated a plurality of times (for example,twice) in the annex section; i.e., in the case where a plurality of sameblock marks are provided in the annex section; the block mark can bedetected with a high level of reliability even when one of the blockmarks cannot be detected by an external disturbance such as, forexample, noise or a defect. In the case where the block mark is repeateda plurality of times with a certain interval, the correct block mark canbe easily distinguishable from a pseudo block mark which is generated bynoise, a defect or the like.

The number and shape of the block marks formed in annex sections 0through 3 can be the same. For example, one block mark 1703 can beprovided in each of annex sections 0 through 3. Alternatively, as shownin FIG. 17, the number and shape of the block marks formed in annexsections 0 through 3 can be different among annex sections 0 through 3.For example, the number of the block marks in annex section 0 can bedifferent from that in annex sections 1 through 3. In this case, alarger number of block marks are provided in annex section 0 than in theother annex sections in order to enhance the reading reliability ofannex section 0 acting as the leading end of the ECC block. In FIG. 17,two block marks 1703 and 1704 are provided in annex section 0, whereasone block mark 1706 is provided in each of annex sections 1 through 3.When the number or shape of the block marks formed in annex section 0 isdifferent from that of annex sections 1 through 3, the block mark inannex section 0 can be easily distinguishable from the block mark of theother annex sections. Thus, the leading address of the ECC block can befinally determined without reading the entirety of the PID sections.

In FIG. 17, the plurality of block marks are provided at the sameposition in terms of the phase of the wobbles. Alternatively, as shownin FIG. 18, the block marks can be provided at positions having a 180degree phase difference of the wobbles (block marks 1703 and 1804).

In this example, each block mark has a physical length of 2 bytes, butthe present invention is not limited to such a length. An optimum designlength which is determined based on the diameter of the optical spot canbe selected. For example, as shown in FIG. 19, the block mark can have aphysical length of 4 bytes.

When the block mark can have a physical length of 4 bytes as shown inFIG. 19, the physical length of the block mark in annex section 0 can bedifferent from that in annex sections 1 through 3. Thus, the readingreliability of the block mark in annex section 0 can be enhanced. Whenthe length of the block mark formed in annex section 0 is different fromthat of annex sections 1 through 3, the block mark in annex section 0can be easily distinguishable from the block mark of the other annexsections.

With reference to FIG. 20, an optical disc medium in which block marksare pre-pits formed in a land will be described. FIG. 20 shows a trackgroove 2002 in such an optical disc medium. The track groove 2002 isobtained by modifying the annex section of the track groove 1602 shownin FIG. 22. In FIG. 20, reference numeral 2001 represents annex section0, and 2005 represents each of annex sections 1 through 3. Block marks2004 are formed in a land 2003 between adjacent portions of the trackgroove 2002 of annex section 0. The block marks 2004 are cut-offportions in the land 2003. When the track groove 2002 is scanned by anoptical spot 2007, the block marks 2004 are scanned in the state ofbeing offset from the center of the optical spot 2007 by a half track.

The block marks 2004 formed on the land 2003 as shown in FIG. 20 can bedetected using a differential signal indicating the difference betweenthe light amounts received by two divided detection areas of a lightreceiving element (e.g., a push-pull signal). The PID sections describedabove are detected using such a differential signal. The block addresscan be detected using a similar differential signal. Therefore, theblock address and the PID sections can be detected without switching thedifferential signal into a sum signal. Thus, a signal detection sectioncan have a simpler circuit configuration.

In the case where a plurality of same block marks are provided in oneannex section like the block marks 2004 in FIG. 20, the number of blockmarks can be different between in annex section 0 and in annex sections1 through 3.

For example, when annex section 0 includes two block marks 2204 andannex sections 1 through 3 each have one block mark 2204, the readingreliability of the block mark in annex section 0 can be enhanced. Whenthe number of the block marks formed in annex section 0 is differentfrom that of annex sections 1 through 3, the block mark in annex section0 can be easily distinguishable from the block mark of the other annexsections.

In each annex section, dummy data can be recorded in order to enhancethe detecting precision of the block mark.

Usable dummy data can be, for example, information including 4T marksand 4T spaces simply in repetition. Thus, the recording mark of thesingle frequency component and the block mark can be frequency-separatedfor easier detection. Thus, the block mark can be more easily detected.

EXAMPLE 13

FIG. 21 shows a PID section 2100 of an optical disc medium according toExample 13 of the present invention. The PID section 2100 is obtained bymodifying the PID0 through PID3 shown in FIG. 22. The PID section 2100includes 52 frames each having 372 bytes, and thus has a length of 19344bytes (=372 bytes×52). The PID section 2100 includes 8-bit PIDinformation 2209, 24-bit block address information 2210, 16-bit IEDinformation 2211, and a 4-bit address mark (AM) 2212 as anidentification mark. The PID information 2209, the block addressinformation 2210 and the IED information 2211 are similar to those ofExample 11.

The address mark 2211 is located at a trailing end of the PID section2100 and is used for detecting a leading end of the PID section which isimmediately subsequent to the PID section 2100. The address mark 2211 isa 4 information unit including sub information “B” in addition to thesub information “1”, “0”, or “S”. The address mark 2211 is representedby combining the sub information “S” and the sub information “B”. Theaddress mark can be a different combination of sub information in eachPID section 2100. For example, as shown in FIG. 21, an address mark 2107of PID3 includes 4-bit information “SSSS”. When this combination isdetected, it is identified that this is the address mark 2107 of PID3.Thus, detection of the identification mark in the annex sectionpreceding the immediately subsequent PID0 or the address of PID0 can beprepared for.

An address mark 2101 of PID0, an address mark 2103 of PID1, and addressmark 2105 of PID2 each include “SBBS”, which is different from that ofthe address mark 2107 of PID3. Since the contents of the address mark ofPID3 are different from those of the address marks of PID0 through PID2,the address mark of PID3 is easily distinguishable from the address markof the other PID sections. Thus, the detection precision of the addressmark of PID3 can be enhanced. Namely, the leading end of the block canbe more easily detected by such a different combination of subinformation.

The address marks of PID0 through PID2 can be formed of the same shapeof wobbles (i.e., the same combination of sub information). For example,the address marks of PID0 through PID2 can all include “SBBS”.

The address marks 2101, 2103, 2105 and 2107 shown in FIG. 21, which haveinformation represented by the wobbles of the track groove, can bedetected using a differential signal indicating the difference betweenthe light amounts received by two divided detection areas of a lightreceiving element (e.g., a push-pull signal). The PID information 2209,the block address information 2210, and the IED information 2211 aredetected using such a differential signal. The block address or theidentification mark preceding each PID section can be detected using asimilar differential signal. Therefore, the leading end of each PIDsection, the leading end of the block, and the block address can bedetected without switching the differential signal into a sum signal anda differential signal. Thus, a signal detection section can have asimpler circuit configuration.

In order to enhance the detection precision of the address marks 2101,2103, 2105 and 2107, dummy data can be recorded in portions of the trackgroove corresponding to the address marks.

Usable dummy data can be, for example, information including 4T marksand 4T spaces simply in repetition. Thus, the recording mark of thesingle frequency component and the block mark can be frequency-separatedfor easier detection. Thus, the block mark can be more easily detected.The address marks shown in FIG. 21 can be detected using thedifferential signal mentioned above. Therefore, the address marks can bedetected by recording proper user data, instead of dummy data, inportions of the track groove corresponding to the address marks.

The identification mark in the annex section and the address mark can beused in combination. The identification mark in the annex section is,for example, a 2-byte mirror mark, and thus is provided at asignificantly high level of positioning precision. Therefore, such acombined use can enhance the precision of the position at whichrecording is started at the time of linking for additional write orrewrite.

EXAMPLE 14

FIG. 23A shows an optical disc apparatus 2300 according to Example 14 ofthe present invention. The optical disc apparatus 2300 reproduces subinformation which is recorded on the optical disc medium by acombination of a plurality of shapes of wobbles described in thepreceding examples, so as to record and reproduce main information. FIG.23 is a flowchart illustrating an operation of the optical discapparatus 2300 shown in FIG. 23A.

The optical disc apparatus 2300 includes a conversion section 2330, areproduction signal calculation section 2308, a focusing positioncontrol section 2309, a tracking position control section 2310, a subinformation detection section 2312, a laser driving section 2313, areproduction signal processing section 2314, and an addressinformation/disc management information processing section 2315. Theconversion section 2330 includes a semiconductor laser 2302, acollimator lens 2303, a beam splitter 2304, a converging section 2305, alight collection lens 2306, a light detection section 2307, and anactuator 2311. The optical disc apparatus 2300 directs a light beamtoward an optical disc medium 2301 so as to read the main informationand the sub information recorded on the optical disc medium 2301 andconvert the main information and the sub information into a reproductionsignal.

With reference to FIGS. 23A and 23B, the light beam emitted by thesemiconductor laser 2302 is collected on an information face of theoptical disc medium 2301 through the collimator lens 2303, the beamsplitter 2304 and the light converging section 2305. The collected lightis then reflected and diffracted by the optical disc medium 2301 and iscollected on the light detection section 2307 through the lightconverging section 2305, the beam splitter 2304 and the light collectionlens 2306. Light receiving elements A, B, C and D of the light detectionsection 2307 each output a voltage signal in accordance with an amountof received light as a reproduction signal 2320 (step S100).

The reproduction signal calculation section 2308 processes thereproduction signal 2320 with addition, subtraction, multiplication ordivision. An FE (focusing error) signal 2321 which is output from thereproduction signal calculation section 2308 as a result of such acalculation is sent to the focusing position control section 2309. A TE(tracking error) signal 2322 which is output from the reproductionsignal calculation section 2308 as a result of such a calculation issent to the tracking position control section 2310. An RF (radiofrequency) signal 2323 which is output from the reproduction signalcalculation section 2308 as a result of such a calculation is sent tothe sub information detection section 2312 and the reproduction signalprocessing section 2314 (step S200).

The focusing position control section 2309 drives the actuator 2311 by avoltage output in accordance with the FE signal 2321 so as to controlthe focusing position of an optical spot on the information face of theoptical disc medium 2301. The tracking position control section 2310drives the actuator 2311 by a voltage output in accordance with the TEsignal 2322 so as to control the tracking position of the optical spoton the information face of the optical disc medium 2301. The opticalspot controlled in terms of the focusing position and the trackingposition is used to read the pre-pits, or marks and spaces on theoptical disc medium 2301. The marks and spaces in the optical discmedium 2301, which is of a phase difference type, reflect light atdifferent reflectances. Thus, the information recorded on the opticaldisc medium 2301 is read. In the case of a push-pull system, the TEsignal 2322 is an output of a difference between the amounts of lightreceived by two light receiving sections of the light detection section2307. The two light receiving sections each including two of the fourlight receiving elements A, B, C and D and are defined by a lineparallel to the tracking direction. Here, the difference is (A+D)−(B+C).The RF signal 2323 is an output of a sum of the amounts of lightreceived by the four light receiving elements A, B, C and D. Here, thesum is (A+B+C+D). In the case of an astigmatism system, the FE signal2321 is an output of (A+C)−(B+D).

The sub information is reproduced in the following manner.

The TE signal 2322 and the RF signal 2323 generated by the reproductionsignal calculation section 2308 are output to the sub informationdetection section 2312 and used for decoding the sub information. Thesub information detected by the sub information detection section 2312is output to the address information/disc management informationprocessing section 2315 and the laser driving section 2313.

As shown in FIG. 34, the sub information detection section 2312 includesa reference clock generation section 3410, a level-sliced pulse signalgeneration section 3411, a third BPF (bandpass filter) 3403 as a blockmark signal detection section, and a sub information generation section3412.

The reference clock generation section 3410 includes a first BPF 3401and a synchronization detection section 3404. The level-sliced pulsesignal generation section 3411 includes a second BPF 3402, a comparator3405 and an integrator 3408. The sub information generation section 3412includes a majority determination section 3406 and a sub informationdecoder 3407.

The first BPF 3401 is designed to have such a filtering constant as toextract a wobble signal modulated into the TE signal 2322. Based on theTE signal 2322, the first BPF 3401 generates an output signal 3401′containing a fundamental wave component having a sine waveformsynchronized with the wobbles in the track groove. The synchronizationdetection section 3404 receives the output signal 3401′ and generates areference clock signal 3404′ in synchronization with the signal readfrom the optical disc medium 2301 (FIG. 23A) (step S300). The referenceclock signal 3404′ is used to synchronize the sub information signal.

The second BPF 3402 is a differential filter for detecting a steep edgeof a sawtooth waveform which is modulated into the TE signal 2322. Inaccordance with the phase (or direction) of the steep edge, the secondBPF 3402 generates an upward or downward differential pulse signal3402′. The differential pulse signal 3402′ is output to the comparator3405. The comparator 3405 compares a regulated slice voltage fed-backthrough the integrator 3408 with the differential pulse signal 3402 andgenerates a level-sliced pulse signal 3405′ with an upward state and adownward state of the differential pulse signal 3402′ being “0” and “1”(step S400). The level-sliced pulse signal 3405′ is output to themajority determination section 3406.

The third BPF 3403 filters the RF signal 2323 so as to detect a blockmark signal 3403′ and finally determine the leading end of the subinformation group (step S500). The detected block mark signal 3403 isoutput to the majority determination section 3406, where the detectedblock mark signal 3403′ is used for timing synchronization.

The majority determination section 3406 compares the number of “0”pulses and “1” pulses of the level-sliced pulse signal 3405′ during aspecified time interval, based on the synchronization signal generatedfrom the reference clock signal 3404′ and the block mark signal 3403′.Then, the majority determination section 3406 outputs the pulses whichoccupy the majority of all the pulses during the specified time intervalto the sub information decoder 3407 as a level-sliced data signal 3406′.The sub information decoder 3407 checks whether there is an error in thelevel-sliced data signal 3406′. When there is no error in thelevel-sliced data signal 3406′, the sub information decoder 3407 outputsthe level-sliced data signal 3406′ as a sub information signal 3420 (forexample, address information) (step S600).

By the above procedure, the sub information signal 3420 recorded on theoptical disc medium 2301 is reproduced. The optical disc apparatus 2300can determine which block of information in the track groove is nowbeing reproduced, based on the address information included in thereproduced sub information signal 3420. When recording the maininformation on the optical disc medium 2301, the address of the blockwhich is immediately previous to the block in which the main informationis to be recorded is determined, and then it is predicted that the nextblock is the block in which the main information is to be recorded. Inthis manner, the main information can be recorded from the leading endof the block of the targeted block.

EXAMPLE 15

A lead-in area and a lead-out area of an optical disc medium accordingto Example 15 of the present invention will be described.

With reference to FIG. 30, a lead-in area and a lead-out area of aconventional optical disc medium 3001 will be described. The opticaldisc medium 3001 includes a lead-in area 3003 provided in an innerperipheral area, a lead-out area 3004 provided in an outer peripheralarea, and a recording and reproduction area provided between the lead-inarea 3003 and the lead-out area 3004. In FIG. 30, a portion 3007 isenlarged. The lead-in area 3003 has pre-pits 3006 formed in advance. Byreading the difference in the reflectance between the pre-pits and theremaining area, the information of “0” or “1” is read. The lead-in area3003 has disc management information recorded in advance. The discmanagement information contains, for example, information on the discreproduction power, servo information, information on the optimumrecording power. The recording and reproduction area 3004 has a trackgroove 3002 formed in advance. By performing tracking control along thetrack groove 3002, rewritable data is recorded in the track groove 3002or data recorded in the track groove 3002 is erased.

In the conventional optical disc medium 3001, the lead-in area 3003 andthe lead-out area 3005 are different from the recording and reproductionarea 3004 in terms of the shape of the pre-pits 3006 and the shape ofthe track groove 3002. Therefore, two tracking systems have to be usedin a switching manner. More specifically, tracking of the differentialphase system (DPD) is used for the lead-in area 3003 and the lead-outarea 3005, and tracking of the push-pull system utilizing diffraction bythe track groove 3002 is used for the recording and reproduction area3004.

In Example 15 of the present invention, an optical disc medium forallowing the same tracking system to be used for the lead-in area,lead-out area, and the recording and reproduction area is provided. Suchan optical disc medium can simplify the tracking operation.

Hereinafter, an optical disc medium according to Example 15 will bedescribed.

FIG. 24 shows an optical disc medium 2400 according to Example 15. Theoptical disc medium 2400 includes a lead-in area 2401, a recording andreproduction area 2402, and a lead-out area 2403. The lead-in area 2401and the lead-out area 2403 have disc management information recorded inadvance. Each of the lead-in area 2401 and the lead-out area 2403 canfurther have an area other than an area for recording the user data,i.e., an area for trial recording. In FIG. 24, the lead-in area 2401 canbe provided in an area from an edge of a circle having a radius of 22.59mm from the center of the optical disc medium 2400 to an edge of acircle having a radius of 24.02 mm from the center of the optical discmedium 2400. The lead-in area 2401 includes a disc management area (anarea from an edge of a circle having a radius of 22.59 mm from thecenter to an edge of a circle having a radius of 24.000 mm from thecenter) having disc management information recorded in advance. Thelead-in area 2401 can also include a rewritable area for trial recordingon the optical disc medium or drive. The information in the discmanagement area is prohibited from being rewritten on principle. In thisexample, the lead-in area 2401 and the lead-out area 2403 mean the discmanagement area.

With reference to FIG. 36, a track groove 3631 formed in a spiral mannerin a recording face of the optical disc medium 2400 will be described.The track groove 3631 is formed in the lead-in area 2401 and thelead-out area 2403. The track groove 3631 is provided with prescribedshape of wobbles 3626, 3627 and 3628 in a periodical manner. The wobbles3626, 3627 and 3628 have different prescribed shapes from each other,and represent sub information (“0”, “1”, “S” or “B”). One type of subinformation (“0”, “1”, “S” or “B”) is represented by one shape ofwobbles 3626, 3627 or 3628. The type of sub information and the shape ofwobbles (wobbles 3626, 3627 or 3628) are in a one-to-one relationship.More specifically, the wobbles 3626 and 3627 having a generally sawtoothshape and the wobbles 3628 having a generally sine wave shape havedifferent rising shapes (or rising gradient) and falling shapes (fallinggradients) as shown in FIG. 36. The disc management information isrepresented by a string of sub information shown by the combination ofthe wobbles 3626, 3627 and 3628.

The difference in the rising gradient and the falling gradient among thewobbles 3626, 3627 and 3628 can be easily detected by a differentialpush-pull detection signal as follows. A scanning laser beam is directedto the track groove 3631, and a differential signal indicating thedifference between the light amounts received by detection areas of alight receiving element divided along a direction perpendicular to thetrack groove 3631 (a radial direction) of the optical disc medium 3400(i.e., a push-pull signal) is generated. Thus, a detection signal havinga rising gradient and a falling gradient which vary in accordance withwhether the sub information is “0” or “1” is obtained. This differencein the rising gradient and the falling gradient can be easily identifiedby, for example, differentiating the detection signal. The type of thesub information can be detected by the size of the value obtained as aresult of differentiation. In the lead-in area 2401 and the lead-outarea 2403, the sub information is used as the disc managementinformation for the recording and reproduction area 2402.

In FIG. 36, a frame 3620 including a block mark 3630 has nine wobbles3628 formed in advance so as to indicate sub information “B”. 52 frames3621 following the block mark 3630 each have a total of 36 wobbles 3626and 3627 so as to indicate sub information “0” and sub information “1”.In the case of the optical disc medium 2400 in this example of the CLVformat, the physical frequency at which the wobbles 3626 and 3627 areformed is constant at fb from the innermost track to the outermosttrack.

With reference to FIGS. 25A and 25B, the lead-in area 2401 and thelead-out area 2403 will be compared with the recording and reproductionarea 2402.

FIG. 25A shows a track groove 2502 in the recording and reproductionarea 2402. A frame 2510 including a block mark 2520 has nine wobbles2528 (sine wave shape) formed in advance so as to indicate subinformation “B”. 52 frames 2511 following the block mark 2520 each havea total of 36 wobbles 2526 and 2527 (sawtooth shape) so as to indicatesub information “0” and sub information “1”. In the case of the opticaldisc medium 2400 in this example of the CLV format, the physicalfrequency at which the wobbles 2526, 2527 and 2528 are formed isconstant at fa from the innermost track to the outermost track (1wobble: 124 channel bit). The wobbling amount of the wobble is constantat 22.5 nm pp.

In the recording and reproduction area 2402, the recording mark isrecorded after being modulated. In this example, a 46D-modulated signalwhich is run-length restricted to be 2T (minimum length) is recorded inthe track groove 2502. The channel bit length at this point is 0.0771μm. The laser light used for recording and reproducing the signal has amean value of the wavelength of 405 nm (+10 nm, −5 nm) and a numericalaperture (NA) of 0.85±0.01.

FIG. 25B shows the track groove 3631 in the lead-in area 2401 and thelead-out area 2403. The details of the track groove 3631 are asdescribed above with reference to FIG. 36. The physical frequency fb atwhich the wobbles 3626, 3627 and 3628 in the lead-in area 2401 and thelead-out area 2403 are formed is ten times higher than the frequency faat which the wobbles 2526, 2527 and 2528 in the recording andreproduction area 2402 are formed. By setting the frequency of thewobbles higher, the amount of information included in a unit area can beincreased.

In the lead-in area 2401 and the lead-out area 2403, a plurality ofwobbles indicate 1-bit sub information. Between the lead-in area 2401and the lead-out area 2403, and the recording and reproduction area2402, the number of wobbles indicating 1-bit information which is theminimum unit of sub information can be different. By reducing the numberof wobbles indicating 1-bit information in the lead-in area 2401 and thelead-out area 2403 as compared to that of the recording and reproductionarea 2402, the wobbles indicating the disc management information can beefficiently formed in relatively small areas of the lead-in area 2401and the lead-out area 2403.

As described above, the lead-in area 2401 and the lead-out area 2403includes the track groove 3631 having prescribed shapes of wobblesformed in a periodical manner, and each shape of the wobbles in thetrack groove 3631 represents the disc management information. Since thewobbles are also formed in a periodical manner in the track groove 2502included in the recording and reproduction area 2402, tracking of thesame system can be used for the entirety of the optical disc medium2400. Since the frequency of the wobbles in the lead-in area 2401 andthe lead-out area 2403 is ten times higher than that of the recordingand reproduction area 2402 and one wobble indicates 1-bit subinformation, the amount of information recorded in a unit area isincreased. Thus, the wobbles indicating the disc management informationcan be efficiently recorded in the limited areas of the lead-in area2401 and the lead-out area 2403.

In this example, the frequency of the wobbles in the lead-in area 2401and the lead-out area 2403 is ten times higher than that of therecording and reproduction area 2402, the present invention is notlimited to such a numerical value.

In this example, sawtooth-shaped wobbles are described. The wobbles arenot limited to such a shape according to the present invention.

In this example, one wobble indicates 1-bit information. A plurality ofwobbles can indicate 1-bit information.

Alternatively, as shown in FIGS. 26A and 26B, the frequency fb of thewobbles in the lead-in area 2401 and the lead-out area 2403 can be lowerthan the frequency fa of the wobbles in the recording and reproductionarea 2402. In this way, the S/N ratio when detecting the wobbles in thelead-in area 2401 and the lead-out area 2403 can be increased. Thus, thereliability of the disc management information in the lead-in area 2401and the lead-out area 2403 can be enhanced.

In this example, the wobbles in the lead-in area 2401 and the lead-outarea 2403 are of the same frequency, which is different from thefrequency of the wobbles in the recording and reproduction area 2402. Inthe case where the disc management information is recorded only in thelead-in area 2401, the frequency of wobbles only in the lead-in area2401 can be different from that of the recording and reproduction area2402.

In this example, the optical disc medium 2400 includes the lead-in area2401 and the lead-out area 2403. The optical disc medium 2400 caninclude only the lead-in area 2401 or only the lead-out area 2403, inaddition to the recording and reproduction area 2402.

EXAMPLE 16

FIGS. 27A and 27B show track grooves 2502 and 2731 of an optical discmedium according to Example 16 of the present invention.

The track groove 2502 shown in FIG. 27A is the same as the track groove2502 described above with reference to FIG. 25A and is formed in therecording and reproduction area 2402 of the optical disc medium 2400shown in FIG. 24. The track groove 2731 shown in FIG. 27B can be formedin the lead-in area 2401 and the lead-out area 2403.

The frame 2510 including the block mark 2520 has nine sine wave-shapedwobbles 2528′ so as to indicate sub information “B”. 52 frames 2511following the block mark 2520 each have a total of 36 sawtooth-shapedwobbles 2526′ and 2527′ so as to indicate sub information “0” and subinformation “1”. In the case of the optical disc medium 2400 in thisexample of the CLV format, the physical frequency at which the wobbles2526, 2527 and 2528 are formed is constant at fa from the innermosttrack to the outermost track (1 wobble: 124 channel bit). The wobbleamplitude representing the wobbling amount of the wobble is constant atCa.

The track grooves shown in FIGS. 27A and 27B are different in the wobbleamplitude, which represents the wobbling amount of the wobbles, fromthose shown in FIGS. 25A and 25B. Whereas the wobble amplitude of thetrack groove 2502 in the recording and reproduction area 2402 in FIG.27A is Ca, the wobble amplitude of the track groove 2731 in the lead-inarea 2401 and the lead-out area 2403 in FIG. 27B is Cb, where Cb>Ca.

The wobble signal amplitude at the time of reproduction is in proportionto the wobbling amount. Therefore, when the wobble amplitude of thelead-in area 2401 and the lead-out area 2403 is larger than the wobbleamplitude of the recording and reproduction area 2402, the S/N ratiowhen detecting the wobbles at the time of reproduction is improved.Thus, the reading reliability of the disc management information can beenhanced.

In this example, the optical disc medium 2400 includes the lead-in area2401 and the lead-out area 2403. The optical disc medium 2400 caninclude only the lead-in area 2401 or only the lead-out area 2403, inaddition to the recording and reproduction area 2402.

EXAMPLE 17

FIGS. 28A and 28B show track grooves 2502 and 2831 of an optical discmedium according to Example 17 of the present invention.

In FIG. 28A, wobbles 2826 are formed by the CLV format, and the physicalfrequency of the wobbles 2826 are constant from the innermost track tothe outermost track. Therefore, the phases of two adjacent wobbles 2826are shifted in accordance with the track position and the radialposition. At the time of reproduction, the influence of the interferenceby the adjacent track is made conspicuous by the phase difference, andthe wobble signal amplitude detected by the reproduction signal variesin a periodical manner by the phase difference. In a wobble in which thevarying wobble signal amplitude is minimum, the S/N ratio is reduced.

The track grooves shown in FIGS. 28A and 28B are different from thoseshown in FIGS. 25A and 25B in the following point. In the track grooves2831, the wobbles 2827 are formed by the CAV format and thus the phasedifference of the wobbles 2827 between two adjacent tracks is alwaysπ/2.

When the wobbles in the recording and reproduction area 2402, thelead-in area 2401 and the lead-out area 2403 are formed by the CAVformat, the wobble signal amplitude at the time of reproduction isconstant. Thus, the detection reliability of the wobbles can beenhanced.

In this example, the phase difference is π/2. Wobbles usually have asteep edge at the position of phase 0 at rising and at the position ofphase T at falling. When the steep edges are made at the positions ofπ/2 and 3×π/2 with π/2×(2n+1) (n is an integer), the influence of thecrosstalk from the adjacent track can be reduced. The phase differenceis not limited to such values but can be any other constant value.

The wobbles in the recording and reproduction area 2402, the lead-inarea 2401 and the lead-out area 2403 can be formed by the ZCLV formatused in the DVD-RAM instead of the CAV format.

By forming the wobbles by the CAV format or the ZCLV format, instead ofthe CLV format, the reliability of the address information reproducedfrom the recording and reproduction area 2402 can be enhanced.

In this example, the optical disc medium 2400 includes the lead-in area2401 and the lead-out area 2403. The optical disc medium 2400 caninclude only the lead-in area 2401 or only the lead-out area 2403, inaddition to the recording and reproduction area 2402.

EXAMPLE 18

FIGS. 29A and 29B show track grooves 2502 and 2931 of an optical discmedium according to Example 18 of the present invention.

The track groove 2502 shown in FIG. 29A is the same as the track groove2502 described above with reference to FIG. 25A and is formed in therecording and reproduction area 2402 of the optical disc medium 2400shown in FIG. 24. The track groove 2931 shown in FIG. 29B can be formedin the lead-in area 2401 and the lead-out area 2403.

The track groove 2502 shown in FIG. 29A has a track pitch (distancebetween two adjacent tracks) of TPa. The main information is recorded inthe track groove 2502 by the groove recording system.

The track grooves shown in FIGS. 29A and 29B are different from thoseshown in FIGS. 25A and 25B in the track pitch. Whereas the track pitchof the track groove 2502 in the recording and reproduction area 2402 inFIG. 29A is TPa, the track pitch of the track groove 2931 in the lead-inarea 2401 and the lead-out area 2403 in FIG. 29B is TPb, where TPb>TPa.When, for example, information recorded on the groove recording systemoptical disc medium having a track pitch TPa=0.32 μm (distance betweentwo adjacent grooves) is reproduced using an optical spot with awavelength of 405 nm and NA of 0.85 as optical constants, the amplitudeof the tracking error signal obtained by the push-pull system issignificantly small. When the track pitch is increased, the amplitude ofthe tracking error signal is increased accordingly. Where the wobblingamount of the wobble is constant, the wobble signal amplitude basicallyincreases in proportion to the amplitude of the tracking error signal.Therefore, when the track pitch is increased, the wobble signalamplitude at the time of reproduction is increased.

Thus, by increasing the track pitch TPb in the lead-in area 2401 and thelead-out area 2403 as compared to the track pitch TPa in the recordingand reproduction area 2402, the S/N ratio when detecting the wobbles canbe enhanced.

Alternatively, when TPb<TPa, the wobbles indicating the disc managementinformation can be efficiently recorded in the limited areas of thelead-in area 2401 and the lead-out area 2403.

In Examples 15 through 18, the frequency of the wobbles, the wobbleamplitude, the phase difference of wobbles from those in an adjacenttrack, the track pitch and the like in the lead-in area 2401 and thelead-out area 2403 are different from those in the recording andreproduction area 2402. A plurality of these factors can be differentbetween the lead-in and lead-out areas 2401 and 2403 and the recordingand reproduction area 2402.

In the track in the disc management area of the lead-in area 2401 andthe lead-out area 2403, no recording mark is formed. Thus, the S/N ratioof the reproduction signal of the disc management area can be increased,and as a result, the reading reliability of the disc management area canbe enhanced.

In this example, the optical disc medium 2400 includes the lead-in area2401 and the lead-out area 2403. The optical disc medium 2400 caninclude only the lead-in area 2401 or only the lead-out area 2403, inaddition to the recording and reproduction area 2402.

EXAMPLE 19

FIG. 35 shows a track groove 3531 of an optical disc medium according toExample 19 of the present invention.

The track groove 3531 shown in FIG. 35 can be formed in the lead-in area2401 and the lead-out area 2403 of the optical disc medium 2400 shown inFIG. 24.

The track groove 3531 shown in FIG. 35 is different from the trackgroove 3631 shown in FIG. 25B in that the track groove 3531 has a singlefrequency recording mark recorded in the lead-in area 2401 and thelead-out area 2403 (i.e., the track groove 3531) in a write once manner.For example, a recording mark having a recording channel bit length of0.0771 μm is recorded by providing a signal having 8T recording marksand 8T spaces repeated in the track groove 3531 having the discmanagement information, in a write once manner. Thus, the informationcan be reproduced by a reproduction apparatus which does not allow fortracking of the push-pull system (apparatus of the DPD system tracking)The compatibility between apparatuses can be improved.

In this example, the optical disc medium 2400 includes the lead-in area2401 and the lead-out area 2403. The optical disc medium 2400 caninclude only the lead-in area 2401 or only the lead-out area 2403, inaddition to the recording and reproduction area 2402.

EXAMPLE 20

FIG. 31 shows a track groove 3101 of an optical disc medium according toExample 20 of the present invention.

In Example 1, the block mark 210 is provided by cutting off the trackgroove 102. In this example, a block mark 3104 is formed by locallyinverting the phase of wobbles 3126 in the track groove 3101. The blockmark 3104 thus formed does not cut off the track groove 3101, and thusinformation can be recorded on the block mark 3104. As a result,overhead can be reduced.

EXAMPLE 21

FIG. 32 shows a track groove 3201 of an optical disc medium according toExample 21 of the present invention.

In Example 1, the block mark 210 is provided by cutting off the trackgroove 102. In this example, a plurality of block marks 3204 a and 3204b are formed by locally inverting the phase of wobbles 3226 in the trackgroove 3201. The block marks 3204 a and 3204 b thus formed do not cutoff the track groove 3201, and in addition, the continuity of the phasesof the wobbles 3226 is kept except for the portion interposed betweenthe block marks 3204 a and 3204 b. Therefore, reproduction can beperformed without substantially varying the phase of the clock of thewobbles and without generating a phase difference in the PLL. Maininformation can be recorded on the block marks 3204 a and 3204 b. As aresult, overhead can be reduced.

EXAMPLE 22

FIG. 33 shows a track groove 3301 of an optical disc medium according toExample 22 of the present invention.

In Example 1, the block mark 210 is provided by cutting off the trackgroove 102. In this example, a block mark 3304 is formed of a wobble3326 having a locally higher frequency than that of the wobbles 26. Theblock mark 3304 thus formed does not cut off the track groove 3301, andthus information can be recorded on the block mark 3304. As a result,overhead can be reduced.

In Examples 1, 4, 5, 7 through 12, 15, 16, and 19 through 22, the trackgroove having a block mark is disclosed. The track groove can beprovided on an optical disc medium without having a block mark.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, a plurality ofprescribed shapes of wobbles are formed in a track groove in which maininformation is recorded on a block-by-block basis. A wobble showsspecific sub information described in a frame obtained by dividing theblock by a prescribed number K. By forming the wobble indicating the subinformation in a plurality of frames, i.e., a plurality of times, in theblock, address information can be formed with no or little overhead. Asingle frequency wobble reproduction signal (i.e., synchronizationsignal) can be obtained. Thus, an optical disc medium suitable for highdensity recording can be provided.

Sub information as a portion of a sub information group indicates asector number of an ID number. When the data is not continuously read,for example, after a seek operation, the sector number or ID number ofthe sector immediately after the seek operation can be read, instead ofthe block mark at the leading end of the block. Thus, the block ID canbe read from an arbitrary sector. By finally determining the block ID byreading only a sector group including a plurality of sectors in theblock, post-processing (data read, data recording, etc.) can beperformed quickly.

The block ID is repeated a plurality of times in one block. Thus, thereading reliability of the block ID can be enhanced.

In a lead-in area and a lead-out area, the disc management informationis indicated by sawtooth-shaped wobbles formed in advance. Thus, thesame tracking system can be used for the entirety of the disc. Theoptical disc apparatus can be simplified.

The wobble frequency is made different between the lead-in and lead-outareas and a recording and reproduction area. The disc management areacan be efficiently recorded in limited areas of the lead-in area in theinner portion and the lead-out area of the outer portion of the disc.

1. An optical disc medium, comprising a track groove having a sinewave-like wobble shape, wherein: the track groove is divided into aplurality of blocks, the plurality of blocks each include a plurality ofunit sections, the plurality of unit sections each include a pluralityof small unit sections, the plurality of small unit sections eachinclude a portion of address information, the portion of addressinformation is represented by a first prescribed wobble shape or asecond prescribed wobble shape, the first and second prescribed wobbleshapes have a single frequency with the sine wave-like wobble shape, thefirst prescribed wobble shape has a gentle rising gradient and a steepfalling gradient by comparison with the sine wave-like wobble shape, thesecond prescribed wobble shape has a steep rising gradient and a gentlefalling gradient by comparison with the sine wave-like wobble shape. 2.A method for reproducing address information from an optical disc mediumaccording to claim 1, the method comprising: irradiating the opticaldisc medium with light; generating an electric signal based on the lightreflected from the optical disc medium; and detecting the portion ofaddress information based on the electric signal.
 3. A method forrecording information on an optical disc medium according to claim 1based on address information recorded on the optical disc medium, themethod comprising: irradiating the optical disc medium with light;generating an electric signal based on the light reflected from theoptical disc medium; detecting the portion of address information basedon the electric signal; and recording information on the optical discmedium based on the detected address information.